diff --git a/change-notes/1.20/analysis-javascript.md b/change-notes/1.20/analysis-javascript.md
index 0814284c5f92..c0933c3a0991 100644
--- a/change-notes/1.20/analysis-javascript.md
+++ b/change-notes/1.20/analysis-javascript.md
@@ -30,7 +30,7 @@
 | Incomplete URL substring sanitization | correctness, security, external/cwe/cwe-020 | Highlights URL sanitizers that are likely to be incomplete, indicating a violation of [CWE-020](https://cwe.mitre.org/data/definitions/20.html). Results shown on LGTM by default. |
 | Incorrect suffix check (`js/incorrect-suffix-check`) | correctness, security, external/cwe/cwe-020 | Highlights error-prone suffix checks based on `indexOf`, indicating a potential violation of [CWE-20](https://cwe.mitre.org/data/definitions/20.html). Results are shown on LGTM by default. |
 | Loop iteration skipped due to shifting (`js/loop-iteration-skipped-due-to-shifting`) | correctness | Highlights code that removes an element from an array while iterating over it, causing the loop to skip over some elements. Results are shown on LGTM by default. |
-| Unbound event handler receiver (`js/unbound-event-handler-receiver`) | Fewer false positive results | Additional ways that class methods can be bound are recognized. |
+| Unused property (`js/unused-property`) | maintainability | Highlights properties that are unused. Results are shown on LGTM by default. |
 | Useless comparison test (`js/useless-comparison-test`) | correctness | Highlights code that is unreachable due to a numeric comparison that is always true or always false. Results are shown on LGTM by default. |
 
 ## Changes to existing queries
@@ -43,9 +43,10 @@
 | Insecure randomness | More results | This rule now flags insecure uses of `crypto.pseudoRandomBytes`. |
 | Reflected cross-site scripting             | Fewer false-positive results. | This rule now recognizes custom sanitizers. |
 | Stored cross-site scripting                | Fewer false-positive results. | This rule now recognizes custom sanitizers. |
+| Unbound event handler receiver (`js/unbound-event-handler-receiver`) | Fewer false positive results | Additional ways that class methods can be bound are recognized. |
 | Uncontrolled data used in network request  | More results                 | This rule now recognizes host values that are vulnerable to injection. |
 | Unused parameter                           | Fewer false-positive results | This rule no longer flags parameters with leading underscore. |
-| Unused variable, import, function or class | Fewer false-positive results | This rule now flags fewer variables that are implictly used by JSX elements, and no longer flags variables with leading underscore. |
+| Unused variable, import, function or class | Fewer false-positive results | This rule now flags fewer variables that are implictly used by JSX elements, no longer flags variables with leading underscore, and no longer flags variables in dead code. |
 | Uncontrolled data used in path expression | Fewer false-positive results | This rule now recognizes the Express `root` option, which prevents path traversal. |
 | Unneeded defensive code | More true-positive results, fewer false-positive results. | This rule now recognizes additional defensive code patterns. |
 | Useless conditional | Fewer results | Additional defensive coding patterns are now ignored. |
diff --git a/javascript/config/suites/javascript/maintainability-more b/javascript/config/suites/javascript/maintainability-more
index f887a26e1797..0f09b9ee4e6b 100644
--- a/javascript/config/suites/javascript/maintainability-more
+++ b/javascript/config/suites/javascript/maintainability-more
@@ -5,6 +5,7 @@
 + semmlecode-javascript-queries/Declarations/DeadStoreOfProperty.ql: /Maintainability/Declarations
 + semmlecode-javascript-queries/Declarations/DuplicateVarDecl.ql: /Maintainability/Declarations
 + semmlecode-javascript-queries/Declarations/UnusedParameter.ql: /Maintainability/Declarations
++ semmlecode-javascript-queries/Declarations/UnusedProperty.ql: /Maintainability/Declarations
 + semmlecode-javascript-queries/Declarations/UnusedVariable.ql: /Maintainability/Declarations
 + semmlecode-javascript-queries/Expressions/UnneededDefensiveProgramming.ql: /Maintainability/Expressions
 + semmlecode-javascript-queries/LanguageFeatures/ArgumentsCallerCallee.ql: /Maintainability/Language Features
diff --git a/javascript/ql/src/Declarations/UnusedParameter.qll b/javascript/ql/src/Declarations/UnusedParameter.qll
index b4fb5cb578a7..b8ff6b1d38e5 100644
--- a/javascript/ql/src/Declarations/UnusedParameter.qll
+++ b/javascript/ql/src/Declarations/UnusedParameter.qll
@@ -1,5 +1,5 @@
 /**
- * This library contains the majority of the 'js/unused-parameter' query implementation.
+ * Provides classes and predicates for the 'js/unused-parameter' query.
  *
  * In order to suppress alerts that are similar to the 'js/unused-parameter' alerts,
  * `isAnAccidentallyUnusedParameter` should be used since it holds iff that alert is active.
diff --git a/javascript/ql/src/Declarations/UnusedProperty.qhelp b/javascript/ql/src/Declarations/UnusedProperty.qhelp
new file mode 100644
index 000000000000..eddbbac28d88
--- /dev/null
+++ b/javascript/ql/src/Declarations/UnusedProperty.qhelp
@@ -0,0 +1,34 @@
+<!DOCTYPE qhelp PUBLIC
+"-//Semmle//qhelp//EN"
+"qhelp.dtd">
+<qhelp>
+	<overview>
+		<p>
+			Unused object properties make code harder to maintain and use. Clients that are unaware that a
+			property is unused may perform nontrivial computations to compute a value that is ultimately
+			unused.
+		</p>
+
+	</overview>
+	<recommendation>
+		<p>Remove the unused property.</p>
+
+	</recommendation>
+	<example>
+
+		<p>
+			In this code, the function <code>f</code> initializes a property <code>prop_a</code> with a
+			call to the function <code>expensiveComputation</code>, but later on, this property is never read.
+			Removing <code>prop</code> would improve code quality and performance.
+		</p>
+
+		<sample src="examples/UnusedProperty.js" />
+
+	</example>
+	<references>
+
+		<li>Coding Horror: <a href="http://blog.codinghorror.com/code-smells/">Code Smells</a>.</li>
+
+
+	</references>
+</qhelp>
diff --git a/javascript/ql/src/Declarations/UnusedProperty.ql b/javascript/ql/src/Declarations/UnusedProperty.ql
new file mode 100644
index 000000000000..9ed31f4ca499
--- /dev/null
+++ b/javascript/ql/src/Declarations/UnusedProperty.ql
@@ -0,0 +1,78 @@
+/**
+ * @name Unused property
+ * @description Unused properties may be a symptom of a bug and should be examined carefully.
+ * @kind problem
+ * @problem.severity recommendation
+ * @id js/unused-property
+ * @tags maintainability
+ * @precision high
+ */
+
+import javascript
+import semmle.javascript.dataflow.LocalObjects
+import UnusedVariable
+import UnusedParameter
+import Expressions.ExprHasNoEffect
+
+predicate hasUnknownPropertyRead(LocalObject obj) {
+  // dynamic reads
+  exists(DataFlow::PropRead r | obj.getAPropertyRead() = r | not exists(r.getPropertyName()))
+  or
+  // reflective reads
+  obj.flowsToExpr(any(EnhancedForLoop l).getIterationDomain())
+  or
+  obj.flowsToExpr(any(InExpr l).getRightOperand())
+  or
+  obj.flowsToExpr(any(SpreadElement e).getOperand())
+  or
+  exists(obj.getAPropertyRead("hasOwnProperty"))
+  or
+  exists(obj.getAPropertyRead("propertyIsEnumerable"))
+}
+
+/**
+ * Holds if `obj` flows to an expression that must have a specific type.
+ */
+predicate flowsToTypeRestrictedExpression(LocalObject obj) {
+  exists (Expr restricted, TypeExpr type |
+    obj.flowsToExpr(restricted) and
+    not type.isAny() |
+    exists (TypeAssertion assertion |
+      type = assertion.getTypeAnnotation() and
+      restricted = assertion.getExpression()
+    )
+    or
+    exists (BindingPattern v |
+      type = v.getTypeAnnotation() and
+      restricted = v.getAVariable().getAnAssignedExpr()
+    )
+    // no need to reason about writes to typed fields, local nodes do not reach them
+  )
+}
+
+from DataFlow::PropWrite write, LocalObject obj, string name
+where
+  write = obj.getAPropertyWrite(name) and
+  not exists(obj.getAPropertyRead(name)) and
+  // `obj` is the only base object for the write: it is not spurious
+  not write.getBase().analyze().getAValue() != obj.analyze().getAValue() and
+  not hasUnknownPropertyRead(obj) and
+  // avoid reporting if the definition is unreachable
+  write.getAstNode().getFirstControlFlowNode().getBasicBlock() instanceof ReachableBasicBlock and
+  // avoid implicitly read properties
+  not (
+    name = "toString" or
+    name = "valueOf" or
+    name.matches("@@%") // @@iterator, for example
+  ) and
+  // avoid flagging properties that a type system requires
+  not flowsToTypeRestrictedExpression(obj) and
+  // flagged by js/unused-local-variable
+  not exists(UnusedLocal l | l.getAnAssignedExpr().getUnderlyingValue().flow() = obj) and
+  // flagged by js/unused-parameter
+  not exists(Parameter p | isAnAccidentallyUnusedParameter(p) |
+    p.getDefault().getUnderlyingValue().flow() = obj
+  ) and
+  // flagged by js/useless-expression
+  not inVoidContext(obj.asExpr())
+select write, "Unused property " + name + "."
diff --git a/javascript/ql/src/Declarations/UnusedVariable.ql b/javascript/ql/src/Declarations/UnusedVariable.ql
index aa361582c10c..2c86549c4ec4 100644
--- a/javascript/ql/src/Declarations/UnusedVariable.ql
+++ b/javascript/ql/src/Declarations/UnusedVariable.ql
@@ -10,23 +10,7 @@
  */
 
 import javascript
-
-/**
- * A local variable that is neither used nor exported, and is not a parameter
- * or a function name.
- */
-class UnusedLocal extends LocalVariable {
-  UnusedLocal() {
-    not exists(getAnAccess()) and
-    not exists(Parameter p | this = p.getAVariable()) and
-    not exists(FunctionExpr fe | this = fe.getVariable()) and
-    not exists(ClassExpr ce | this = ce.getVariable()) and
-    not exists(ExportDeclaration ed | ed.exportsAs(this, _)) and
-    not exists(LocalVarTypeAccess type | type.getVariable() = this) and
-    // common convention: variables with leading underscore are intentionally unused
-    getName().charAt(0) != "_"
-  }
-}
+import UnusedVariable
 
 /**
  * Holds if `v` is mentioned in a JSDoc comment in the same file, and that file
@@ -206,6 +190,10 @@ predicate unusedImports(ImportVarDeclProvider provider, string msg) {
 
 from ASTNode sel, string msg
 where
-  unusedNonImports(sel, msg) or
-  unusedImports(sel, msg)
+  (
+    unusedNonImports(sel, msg) or
+    unusedImports(sel, msg)
+  ) and
+  // avoid reporting if the definition is unreachable
+  sel.getFirstControlFlowNode().getBasicBlock() instanceof ReachableBasicBlock
 select sel, msg
diff --git a/javascript/ql/src/Declarations/UnusedVariable.qll b/javascript/ql/src/Declarations/UnusedVariable.qll
new file mode 100644
index 000000000000..143a8c5e0746
--- /dev/null
+++ b/javascript/ql/src/Declarations/UnusedVariable.qll
@@ -0,0 +1,22 @@
+/**
+ * Provides classes and predicates for the 'js/unused-local-variable' query.
+ */
+
+import javascript
+
+/**
+ * A local variable that is neither used nor exported, and is not a parameter
+ * or a function name.
+ */
+class UnusedLocal extends LocalVariable {
+  UnusedLocal() {
+    not exists(getAnAccess()) and
+    not exists(Parameter p | this = p.getAVariable()) and
+    not exists(FunctionExpr fe | this = fe.getVariable()) and
+    not exists(ClassExpr ce | this = ce.getVariable()) and
+    not exists(ExportDeclaration ed | ed.exportsAs(this, _)) and
+    not exists(LocalVarTypeAccess type | type.getVariable() = this) and
+    // common convention: variables with leading underscore are intentionally unused
+    getName().charAt(0) != "_"
+  }
+}
diff --git a/javascript/ql/src/Declarations/examples/UnusedProperty.js b/javascript/ql/src/Declarations/examples/UnusedProperty.js
new file mode 100644
index 000000000000..3d1441d430b2
--- /dev/null
+++ b/javascript/ql/src/Declarations/examples/UnusedProperty.js
@@ -0,0 +1,8 @@
+function f() {
+	var o = {
+		prop_a: expensiveComputation(),
+		prop_b: anotherComputation()
+	};
+
+	return o.prop_b;
+}
diff --git a/javascript/ql/src/Expressions/ExprHasNoEffect.ql b/javascript/ql/src/Expressions/ExprHasNoEffect.ql
index c2dbe038963d..3ceda6fa29bc 100644
--- a/javascript/ql/src/Expressions/ExprHasNoEffect.ql
+++ b/javascript/ql/src/Expressions/ExprHasNoEffect.ql
@@ -16,40 +16,7 @@ import javascript
 import DOMProperties
 import semmle.javascript.frameworks.xUnit
 import semmle.javascript.RestrictedLocations
-
-/**
- * Holds if `e` appears in a syntactic context where its value is discarded.
- */
-predicate inVoidContext(Expr e) {
-  exists(ExprStmt parent |
-    // e is a toplevel expression in an expression statement
-    parent = e.getParent() and
-    // but it isn't an HTML attribute or a configuration object
-    not exists(TopLevel tl | tl = parent.getParent() |
-      tl instanceof CodeInAttribute
-      or
-      // if the toplevel in its entirety is of the form `({ ... })`,
-      // it is probably a configuration object (e.g., a require.js build configuration)
-      tl.getNumChildStmt() = 1 and e.stripParens() instanceof ObjectExpr
-    )
-  )
-  or
-  exists(SeqExpr seq, int i, int n |
-    e = seq.getOperand(i) and
-    n = seq.getNumOperands()
-  |
-    i < n - 1 or inVoidContext(seq)
-  )
-  or
-  exists(ForStmt stmt | e = stmt.getUpdate())
-  or
-  exists(ForStmt stmt | e = stmt.getInit() |
-    // Allow the pattern `for(i; i < 10; i++)`
-    not e instanceof VarAccess
-  )
-  or
-  exists(LogicalBinaryExpr logical | e = logical.getRightOperand() and inVoidContext(logical))
-}
+import ExprHasNoEffect
 
 /**
  * Holds if `e` is of the form `x;` or `e.p;` and has a JSDoc comment containing a tag.
diff --git a/javascript/ql/src/Expressions/ExprHasNoEffect.qll b/javascript/ql/src/Expressions/ExprHasNoEffect.qll
new file mode 100644
index 000000000000..858f719ba0a0
--- /dev/null
+++ b/javascript/ql/src/Expressions/ExprHasNoEffect.qll
@@ -0,0 +1,39 @@
+/**
+ * Provides classes and predicates for the 'js/useless-expression' query.
+ */
+
+import javascript
+
+/**
+ * Holds if `e` appears in a syntactic context where its value is discarded.
+ */
+predicate inVoidContext(Expr e) {
+  exists(ExprStmt parent |
+    // e is a toplevel expression in an expression statement
+    parent = e.getParent() and
+    // but it isn't an HTML attribute or a configuration object
+    not exists(TopLevel tl | tl = parent.getParent() |
+      tl instanceof CodeInAttribute
+      or
+      // if the toplevel in its entirety is of the form `({ ... })`,
+      // it is probably a configuration object (e.g., a require.js build configuration)
+      tl.getNumChildStmt() = 1 and e.stripParens() instanceof ObjectExpr
+    )
+  )
+  or
+  exists(SeqExpr seq, int i, int n |
+    e = seq.getOperand(i) and
+    n = seq.getNumOperands()
+  |
+    i < n - 1 or inVoidContext(seq)
+  )
+  or
+  exists(ForStmt stmt | e = stmt.getUpdate())
+  or
+  exists(ForStmt stmt | e = stmt.getInit() |
+    // Allow the pattern `for(i; i < 10; i++)`
+    not e instanceof VarAccess
+  )
+  or
+  exists(LogicalBinaryExpr logical | e = logical.getRightOperand() and inVoidContext(logical))
+}
diff --git a/javascript/ql/src/semmle/javascript/dataflow/DataFlow.qll b/javascript/ql/src/semmle/javascript/dataflow/DataFlow.qll
index 87feadd43610..0a1d40411d59 100644
--- a/javascript/ql/src/semmle/javascript/dataflow/DataFlow.qll
+++ b/javascript/ql/src/semmle/javascript/dataflow/DataFlow.qll
@@ -583,7 +583,18 @@ module DataFlow {
 
     override string getPropertyName() { result = prop.getName() }
 
-    override Node getRhs() { result = parameterNode(prop.getParameter()) }
+    override Node getRhs() {
+      exists(Parameter param, Node paramNode |
+        param = prop.getParameter() and
+        parameterNode(paramNode, param)
+        |
+        result = paramNode
+        or
+        // special case: there is no SSA flow step for unused parameters
+        paramNode instanceof UnusedParameterNode and
+        result = param.getDefault().flow()
+      )
+    }
 
     override ControlFlowNode getWriteNode() { result = prop.getParameter() }
   }
diff --git a/javascript/ql/src/semmle/javascript/dataflow/LocalObjects.qll b/javascript/ql/src/semmle/javascript/dataflow/LocalObjects.qll
new file mode 100644
index 000000000000..c8f1bcf0f0df
--- /dev/null
+++ b/javascript/ql/src/semmle/javascript/dataflow/LocalObjects.qll
@@ -0,0 +1,80 @@
+/**
+ * Provides classes for the local objects that the dataflow library can reason about soundly.
+ */
+
+import javascript
+
+/**
+ * Holds if the dataflow library can not track flow through `escape` due to `cause`.
+ */
+private predicate isEscape(DataFlow::Node escape, string cause) {
+  escape = any(DataFlow::InvokeNode invk).getAnArgument() and cause = "argument"
+  or
+  escape = any(DataFlow::FunctionNode fun).getAReturn() and cause = "return"
+  or
+  escape = any(ThrowStmt t).getExpr().flow() and cause = "throw"
+  or
+  escape = any(DataFlow::GlobalVariable v).getAnAssignedExpr().flow() and cause = "global"
+  or
+  escape = any(DataFlow::PropWrite write).getRhs() and cause = "heap"
+  or
+  escape = any(ExportDeclaration e).getSourceNode(_) and cause = "export"
+  or
+  exists (WithStmt with, Assignment assign |
+    with.mayAffect(assign.getLhs()) and
+    assign.getRhs().flow() = escape and
+    cause = "heap"
+  )
+}
+
+private DataFlow::Node getAnEscape() {
+  isEscape(result, _)
+}
+
+/**
+ * Holds if `n` can flow to a `this`-variable.
+ */
+private predicate exposedAsReceiver(DataFlow::SourceNode n) {
+  // pragmatic limitation: guarantee for object literals only
+  not n instanceof DataFlow::ObjectLiteralNode
+  or
+  exists(AbstractValue v | n.getAPropertyWrite().getRhs().analyze().getALocalValue() = v |
+    v.isIndefinite(_) or
+    exists(ThisExpr dis | dis.getBinder() = v.(AbstractCallable).getFunction())
+  )
+  or
+  n.flowsToExpr(any(FunctionBindExpr bind).getObject())
+  or
+  // technically, the builtin prototypes could have a `this`-using function through which this node escapes, but we ignore that here
+  // (we also ignore `o['__' + 'proto__'] = ...`)
+  exists(n.getAPropertyWrite("__proto__"))
+  or
+  // could check the assigned value of all affected variables, but it is unlikely to matter in practice
+  exists(WithStmt with | n.flowsToExpr(with.getExpr()))
+}
+
+/**
+ * An object that is entirely local, in the sense that the dataflow
+ * library models all of its flow.
+ *
+ * All uses of this node are modeled by `this.flowsTo(_)` and related predicates.
+ */
+class LocalObject extends DataFlow::SourceNode {
+  LocalObject() {
+    // pragmatic limitation: object literals only
+    this instanceof DataFlow::ObjectLiteralNode and
+    not flowsTo(getAnEscape()) and
+    not exposedAsReceiver(this)
+  }
+
+  predicate hasOwnProperty(string name) {
+    // the property is defined in the initializer,
+    any(DataFlow::PropWrite write).writes(this, name, _) and
+    // and it is never deleted
+    not exists(DeleteExpr del, DataFlow::PropRef ref |
+      del.getOperand().flow() = ref and
+      flowsTo(ref.getBase()) and
+      (ref.getPropertyName() = name or not exists(ref.getPropertyName()))
+    )
+  }
+}
diff --git a/javascript/ql/src/semmle/javascript/dataflow/internal/InterProceduralTypeInference.qll b/javascript/ql/src/semmle/javascript/dataflow/internal/InterProceduralTypeInference.qll
index 459cfe7c2bae..3d24b152abc1 100644
--- a/javascript/ql/src/semmle/javascript/dataflow/internal/InterProceduralTypeInference.qll
+++ b/javascript/ql/src/semmle/javascript/dataflow/internal/InterProceduralTypeInference.qll
@@ -6,6 +6,7 @@
 
 import javascript
 import AbstractValuesImpl
+import semmle.javascript.dataflow.LocalObjects
 
 /**
  * Flow analysis for `this` expressions inside functions.
@@ -230,3 +231,49 @@ private class TypeInferredCalleeWithAnalyzedReturnFlow extends CallWithNonLocalA
 
   override AnalyzedFunction getACallee() { result = fun }
 }
+
+/**
+ * Holds if `call` uses `receiver` as its only receiver value.
+ */
+pragma[noinline]
+private predicate hasDefiniteReceiver(
+  DataFlow::MethodCallNode call, LocalObject receiver
+) {
+  call = receiver.getAMethodCall() and
+  exists (DataFlow::AnalyzedNode receiverNode, AbstractValue abstractLocalReceiver |
+    receiverNode = call.getReceiver() and
+    not receiverNode.getALocalValue().isIndefinite(_) and
+    abstractLocalReceiver = receiver.analyze().getALocalValue() and
+    forall(DataFlow::AbstractValue v |
+      receiverNode.getALocalValue() = v |
+      v = abstractLocalReceiver
+    )
+  )
+}
+
+/**
+ * Enables inter-procedural type inference for the return value of a
+ * method call to a flow-insensitively type-inferred callee.
+ */
+private class TypeInferredMethodWithAnalyzedReturnFlow extends CallWithNonLocalAnalyzedReturnFlow {
+  DataFlow::FunctionNode fun;
+
+  TypeInferredMethodWithAnalyzedReturnFlow() {
+    exists(LocalObject obj, DataFlow::PropWrite write, string name |
+      this.(DataFlow::MethodCallNode).getMethodName() = name and
+      obj.hasOwnProperty(name) and
+      hasDefiniteReceiver(this, obj) and
+      // include all potential callees
+      // by construction, there are no unknown methods on `obj`
+      write = obj.getAPropertyWrite() and
+      fun.flowsTo(write.getRhs()) and
+      (
+        not exists(write.getPropertyName())
+        or
+        write.getPropertyName() = name
+      )
+    )
+  }
+
+  override AnalyzedFunction getACallee() { result = fun }
+}
\ No newline at end of file
diff --git a/javascript/ql/test/library-tests/LocalObjects/LocalObject.expected b/javascript/ql/test/library-tests/LocalObjects/LocalObject.expected
new file mode 100644
index 000000000000..45d5a05f662d
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/LocalObject.expected
@@ -0,0 +1,25 @@
+| method-calls.js:2:11:7:2 | {\\n\\t\\tm1: ... }; }\\n\\t} |
+| method-calls.js:11:23:11:24 | {} |
+| method-calls.js:16:11:16:12 | {} |
+| method-calls.js:25:11:25:17 | {m: f1} |
+| method-calls.js:29:11:29:17 | {m: f2} |
+| method-calls.js:34:12:34:18 | {m: f3} |
+| method-calls.js:38:15:38:21 | {m: f4} |
+| method-calls.js:46:16:46:28 | {m: () => 42} |
+| method-calls.js:50:17:50:29 | {m: () => 42} |
+| method-calls.js:54:16:54:28 | {m: () => 42} |
+| method-calls.js:57:16:57:28 | {m: () => 42} |
+| tst.js:3:15:3:16 | {} |
+| tst.js:4:15:4:33 | { f: function(){} } |
+| tst.js:5:15:5:31 | { [unknown]: 42 } |
+| tst.js:38:15:38:23 | { p: 42 } |
+| tst.js:42:15:42:30 | { p: 42, q: 42 } |
+| tst.js:52:23:52:24 | {} |
+| tst.js:56:20:56:35 | { p: 42, p: 42 } |
+| tst.js:59:20:59:28 | { p: 42 } |
+| tst.js:63:20:63:28 | { p: 42 } |
+| tst.js:68:16:68:24 | { p: 42 } |
+| tst.js:73:15:73:17 | { } |
+| tst.js:76:15:76:23 | { p: 42 } |
+| tst.js:77:15:77:25 | { p: true } |
+| tst.js:82:17:82:18 | {} |
diff --git a/javascript/ql/test/library-tests/LocalObjects/LocalObject.ql b/javascript/ql/test/library-tests/LocalObjects/LocalObject.ql
new file mode 100644
index 000000000000..d2bfd93b5368
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/LocalObject.ql
@@ -0,0 +1,4 @@
+import javascript
+import semmle.javascript.dataflow.LocalObjects
+
+select any(LocalObject n)
diff --git a/javascript/ql/test/library-tests/LocalObjects/LocalObject_hasOwnProperty.expected b/javascript/ql/test/library-tests/LocalObjects/LocalObject_hasOwnProperty.expected
new file mode 100644
index 000000000000..ef9d64c3c70a
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/LocalObject_hasOwnProperty.expected
@@ -0,0 +1,22 @@
+| method-calls.js:2:11:7:2 | {\\n\\t\\tm1: ... }; }\\n\\t} | m1 |
+| method-calls.js:2:11:7:2 | {\\n\\t\\tm1: ... }; }\\n\\t} | m2 |
+| method-calls.js:2:11:7:2 | {\\n\\t\\tm1: ... }; }\\n\\t} | m3 |
+| method-calls.js:2:11:7:2 | {\\n\\t\\tm1: ... }; }\\n\\t} | m4 |
+| method-calls.js:25:11:25:17 | {m: f1} | m |
+| method-calls.js:29:11:29:17 | {m: f2} | m |
+| method-calls.js:34:12:34:18 | {m: f3} | m |
+| method-calls.js:38:15:38:21 | {m: f4} | m |
+| method-calls.js:46:16:46:28 | {m: () => 42} | m |
+| method-calls.js:50:17:50:29 | {m: () => 42} | m |
+| method-calls.js:54:16:54:28 | {m: () => 42} | m |
+| method-calls.js:57:16:57:28 | {m: () => 42} | m |
+| tst.js:4:18:4:36 | { f: function(){} } | f |
+| tst.js:38:18:38:26 | { p: 42 } | p |
+| tst.js:42:18:42:33 | { p: 42, q: 42 } | p |
+| tst.js:42:18:42:33 | { p: 42, q: 42 } | q |
+| tst.js:56:20:56:35 | { p: 42, p: 42 } | p |
+| tst.js:59:20:59:28 | { p: 42 } | p |
+| tst.js:63:20:63:28 | { p: 42 } | p |
+| tst.js:68:19:68:27 | { p: 42 } | p |
+| tst.js:76:18:76:26 | { p: 42 } | p |
+| tst.js:77:18:77:28 | { p: true } | p |
diff --git a/javascript/ql/test/library-tests/LocalObjects/LocalObject_hasOwnProperty.ql b/javascript/ql/test/library-tests/LocalObjects/LocalObject_hasOwnProperty.ql
new file mode 100644
index 000000000000..28dfabddb38e
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/LocalObject_hasOwnProperty.ql
@@ -0,0 +1,6 @@
+import javascript
+import semmle.javascript.dataflow.LocalObjects
+
+from LocalObject src, string name
+where src.hasOwnProperty(name)
+select src, name
diff --git a/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInference.expected b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInference.expected
new file mode 100644
index 000000000000..afab24f56bca
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInference.expected
@@ -0,0 +1,12 @@
+| method-calls.js:8:2:8:8 | o1.m1() | object |
+| method-calls.js:9:2:9:8 | o1.m2() | object |
+| method-calls.js:12:2:12:7 | o.m3() | boolean, class, date, function, null, number, object, regular expression,string or undefined |
+| method-calls.js:21:2:21:7 | o2.m() | boolean, class, date, function, null, number, object, regular expression,string or undefined |
+| method-calls.js:25:11:25:21 | {m: f1}.m() | object |
+| method-calls.js:30:11:30:16 | o2.m() | object |
+| method-calls.js:34:11:34:23 | ({m: f3}).m() | object |
+| method-calls.js:41:11:41:16 | o4.m() | boolean, class, date, function, null, number, object, regular expression,string or undefined |
+| method-calls.js:47:12:47:16 | o.m() | boolean, class, date, function, null, number, object, regular expression,string or undefined |
+| method-calls.js:51:12:51:16 | o.m() | boolean, class, date, function, null, number, object, regular expression,string or undefined |
+| method-calls.js:55:12:55:16 | o.m() | boolean, class, date, function, null, number, object, regular expression,string or undefined |
+| method-calls.js:60:12:60:16 | o.m() | boolean, class, date, function, null, number, object, regular expression,string or undefined |
diff --git a/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInference.ql b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInference.ql
new file mode 100644
index 000000000000..b5224bed0676
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInference.ql
@@ -0,0 +1,4 @@
+import javascript
+
+from DataFlow::MethodCallNode call
+select call, call.analyze().ppTypes()
diff --git a/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInferenceUsage.expected b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInferenceUsage.expected
new file mode 100644
index 000000000000..257fd863f811
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInferenceUsage.expected
@@ -0,0 +1,4 @@
+| method-calls.js:25:11:25:21 | {m: f1}.m() | method-calls.js:26:2:26:3 | v1 | method-calls.js:24:23:24:24 | object literal |
+| method-calls.js:30:11:30:16 | o2.m() | method-calls.js:31:2:31:3 | v2 | method-calls.js:28:23:28:24 | object literal |
+| method-calls.js:34:11:34:23 | ({m: f3}).m() | method-calls.js:35:2:35:3 | v3 | method-calls.js:33:23:33:24 | object literal |
+| method-calls.js:41:11:41:16 | o4.m() | method-calls.js:42:2:42:3 | v4 | file://:0:0:0:0 | indefinite value (call) |
diff --git a/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInferenceUsage.ql b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInferenceUsage.ql
new file mode 100644
index 000000000000..e35d82a37370
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/MethodCallTypeInferenceUsage.ql
@@ -0,0 +1,5 @@
+import javascript
+
+from DataFlow::MethodCallNode call, DataFlow::Node use
+where call.flowsTo(use) and use != call and not exists(use.getASuccessor())
+select call, use, use.analyze().getAValue()
\ No newline at end of file
diff --git a/javascript/ql/test/library-tests/LocalObjects/method-calls.js b/javascript/ql/test/library-tests/LocalObjects/method-calls.js
new file mode 100644
index 000000000000..79947632eea3
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/method-calls.js
@@ -0,0 +1,63 @@
+(function() {
+	var o1 = {
+		m1: function(){ return {}; },
+		m2: function(){ return {}; },
+		m3: function(){ return {}; },
+		m4: function(){ return {}; }
+	};
+	o1.m1(); // analyzed precisely
+	o1.m2(); // analyzed precisely
+	unknown(o1.m2);
+	var o = unknown? o1: {};
+	o.m3(); // not analyzed precisely: `o1` is not the only receiver.
+	var m4 = o.m4;
+	m4(); // (not a method call)
+
+	var o2 = {};
+	o2.m = function() { return {}; };
+	// not analyzed precisely: `m` may be in the prototype since `m`
+	// is not in the initializer, and we do not attempt to reason flow
+	// sensitively beyond that at the moment
+	o2.m();
+});
+(function(){
+	function f1(){return {};}
+	var v1 = {m: f1}.m(); // analyzed precisely
+	v1 === true;
+
+	function f2(){return {};}
+	var o2 = {m: f2};
+	var v2 = o2.m(); // analyzed precisely
+	v2 === true;
+
+	function f3(){return {};}
+	var v3 = ({m: f3}).m(); // analyzed precisely
+	v3 === true;
+
+	function f4(){return {};}
+	var { o4 } = {m: f4};
+	// not analyzed precisely: o4 is from a destructuring assignment
+	// (and it is even `undefined` in this case)
+	var v4 = o4.m();
+	v4 === true;
+});
+
+(function(){
+	(function(o = {m: () => 42}){
+		var v1 = o.m(); // not analyzed precisely: `o` may be `unknown`
+	})(unknown);
+
+	function f(o = {m: () => 42}){
+		var v2 = o.m(); // not analyzed precisely: `o` may be `unknown`
+	};
+	f(unknown);
+	(function(o = {m: () => 42}){
+		var v3 = o.m(); // not analyzed precisely: `o.m` may be `unknown`
+	})({m: unknown});
+	(function(o = {m: () => 42}){
+		// not analyzed precisely: we only support unique receivers at
+		// the moment
+		var v4 = o.m();
+	})({m: () => true});
+
+});
diff --git a/javascript/ql/test/library-tests/LocalObjects/tst.js b/javascript/ql/test/library-tests/LocalObjects/tst.js
new file mode 100644
index 000000000000..fae906604a74
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/tst.js
@@ -0,0 +1,93 @@
+(function localSource(){
+
+	let local1 = {};
+	let local2 = { f: function(){} };
+	let local3 = { [unknown]: 42 };
+
+	unknown({});
+
+	function known(){}
+	known({});
+
+	function known_escaping(e){unknown(e)}
+	known_escaping({});
+
+	(function(){return {}});
+
+	(function(){throw {}});
+
+	global = {};
+
+	this.p = {};
+
+	let local_in_with;
+	with (unknown) {
+		local_in_with = {};
+	}
+
+	with({}){}
+
+	({ m: function(){ this; } });
+	({ m: unknown });
+	let indirectlyUnknown = unknown? unknown: function(){};
+	({ m: indirectlyUnknown });
+});
+
+(function localProperty(){
+
+	let local1 = { p: 42 };
+	local1.p;
+	local1.p;
+
+	let local2 = { p: 42, q: 42 };
+	local2.p;
+	local2.p;
+	local2.q = 42;
+	local2 = 42;
+
+	let nonObject = function(){}
+	nonObject.p = 42;
+	nonObject.p;
+
+	let nonInitializer = {};
+	nonInitializer.p = 42;
+	nonInitializer.p;
+
+	let overridden1 = { p: 42, p: 42 };
+	overridden1.p;
+
+	let overridden2 = { p: 42 };
+	overridden2.p = 42;
+	overridden2.p;
+
+	let overridden3 = { p: 42 };
+	overridden3[x] = 42;
+	overridden3.p;
+
+	function f(o) {
+		let local3 = { p: 42 };
+		o = o || local3;
+		o.p;
+	}
+
+	let local4 = { };
+	local4.p;
+
+	let local5 = { p: 42 },
+	    local6 = { p: true };
+	(unknown? local5: local6).p; // could support this with a bit of extra work
+
+	(function(semiLocal7){
+		if(unknown)
+			semiLocal7 = {};
+		semiLocal7.p = 42;
+	});
+
+});
+
+(function (){
+	let bound = {};
+	bound::unknown();
+});
+
+// semmle-extractor-options: --experimental
diff --git a/javascript/ql/test/library-tests/LocalObjects/tst.ts b/javascript/ql/test/library-tests/LocalObjects/tst.ts
new file mode 100644
index 000000000000..1f2794c0e5e1
--- /dev/null
+++ b/javascript/ql/test/library-tests/LocalObjects/tst.ts
@@ -0,0 +1,6 @@
+class C  {
+    constructor(
+        private readonly F: { timeout: number } = { timeout: 1500 }
+    ) {
+    }
+}
diff --git a/javascript/ql/test/library-tests/PropWrite/PropWrite.expected b/javascript/ql/test/library-tests/PropWrite/PropWrite.expected
index 091d4f792b65..fe5fd6f52968 100644
--- a/javascript/ql/test/library-tests/PropWrite/PropWrite.expected
+++ b/javascript/ql/test/library-tests/PropWrite/PropWrite.expected
@@ -2,6 +2,10 @@
 | classes.ts:4:3:4:24 | instanc ...  foo(); |
 | classes.ts:8:3:8:39 | constru ... eld) {} |
 | classes.ts:8:15:8:35 | public  ... erField |
+| classes.ts:12:5:12:68 | constru ... + 42; } |
+| classes.ts:12:17:12:37 | public  ... erField |
+| classes.ts:16:5:16:46 | constru ...  {}) {} |
+| classes.ts:16:17:16:37 | public  ... erField |
 | tst.js:3:5:3:8 | x: 4 |
 | tst.js:4:5:6:5 | func: f ... ;\\n    } |
 | tst.js:7:5:9:5 | f() {\\n  ... ;\\n    } |
diff --git a/javascript/ql/test/library-tests/PropWrite/PropWriteBase.expected b/javascript/ql/test/library-tests/PropWrite/PropWriteBase.expected
index 241e2c7d583f..1d8e78556df6 100644
--- a/javascript/ql/test/library-tests/PropWrite/PropWriteBase.expected
+++ b/javascript/ql/test/library-tests/PropWrite/PropWriteBase.expected
@@ -1,5 +1,7 @@
 | classes.ts:4:3:4:24 | instanc ...  foo(); | classes.ts:3:21:3:20 | this |
 | classes.ts:8:15:8:35 | public  ... erField | classes.ts:8:3:8:2 | this |
+| classes.ts:12:17:12:37 | public  ... erField | classes.ts:12:5:12:4 | this |
+| classes.ts:16:17:16:37 | public  ... erField | classes.ts:16:5:16:4 | this |
 | tst.js:3:5:3:8 | x: 4 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} |
 | tst.js:4:5:6:5 | func: f ... ;\\n    } | tst.js:2:11:10:1 | {\\n    x ...     }\\n} |
 | tst.js:7:5:9:5 | f() {\\n  ... ;\\n    } | tst.js:2:11:10:1 | {\\n    x ...     }\\n} |
diff --git a/javascript/ql/test/library-tests/PropWrite/PropWritePropName.expected b/javascript/ql/test/library-tests/PropWrite/PropWritePropName.expected
index d2ac2679d25e..f00531e92e6d 100644
--- a/javascript/ql/test/library-tests/PropWrite/PropWritePropName.expected
+++ b/javascript/ql/test/library-tests/PropWrite/PropWritePropName.expected
@@ -2,6 +2,10 @@
 | classes.ts:4:3:4:24 | instanc ...  foo(); | instanceField |
 | classes.ts:8:3:8:39 | constru ... eld) {} | constructor |
 | classes.ts:8:15:8:35 | public  ... erField | parameterField |
+| classes.ts:12:5:12:68 | constru ... + 42; } | constructor |
+| classes.ts:12:17:12:37 | public  ... erField | parameterField |
+| classes.ts:16:5:16:46 | constru ...  {}) {} | constructor |
+| classes.ts:16:17:16:37 | public  ... erField | parameterField |
 | tst.js:3:5:3:8 | x: 4 | x |
 | tst.js:4:5:6:5 | func: f ... ;\\n    } | func |
 | tst.js:7:5:9:5 | f() {\\n  ... ;\\n    } | f |
diff --git a/javascript/ql/test/library-tests/PropWrite/PropWriteRhs.expected b/javascript/ql/test/library-tests/PropWrite/PropWriteRhs.expected
index 68c111317538..42087edc9c1e 100644
--- a/javascript/ql/test/library-tests/PropWrite/PropWriteRhs.expected
+++ b/javascript/ql/test/library-tests/PropWrite/PropWriteRhs.expected
@@ -2,6 +2,11 @@
 | classes.ts:4:3:4:24 | instanc ...  foo(); | classes.ts:4:19:4:23 | foo() |
 | classes.ts:8:3:8:39 | constru ... eld) {} | classes.ts:8:3:8:39 | constru ... eld) {} |
 | classes.ts:8:15:8:35 | public  ... erField | classes.ts:8:22:8:35 | parameterField |
+| classes.ts:12:5:12:68 | constru ... + 42; } | classes.ts:12:5:12:68 | constru ... + 42; } |
+| classes.ts:12:17:12:37 | public  ... erField | classes.ts:12:24:12:37 | parameterField |
+| classes.ts:16:5:16:46 | constru ...  {}) {} | classes.ts:16:5:16:46 | constru ...  {}) {} |
+| classes.ts:16:17:16:37 | public  ... erField | classes.ts:16:24:16:37 | parameterField |
+| classes.ts:16:17:16:37 | public  ... erField | classes.ts:16:41:16:42 | {} |
 | tst.js:3:5:3:8 | x: 4 | tst.js:3:8:3:8 | 4 |
 | tst.js:4:5:6:5 | func: f ... ;\\n    } | tst.js:4:11:6:5 | functio ... ;\\n    } |
 | tst.js:7:5:9:5 | f() {\\n  ... ;\\n    } | tst.js:7:6:9:5 | () {\\n   ... ;\\n    } |
diff --git a/javascript/ql/test/library-tests/PropWrite/classes.ts b/javascript/ql/test/library-tests/PropWrite/classes.ts
index 7fff3a522c16..fed5f11c43e6 100644
--- a/javascript/ql/test/library-tests/PropWrite/classes.ts
+++ b/javascript/ql/test/library-tests/PropWrite/classes.ts
@@ -7,3 +7,11 @@ class InstanceField {
 class ParameterField {
   constructor(public parameterField) {}
 }
+
+class ParameterFieldInit  {
+    constructor(public parameterField = {}) { parameterField + 42; }
+}
+
+class ParameterFieldInitUnused  {
+    constructor(public parameterField = {}) {}
+}
diff --git a/javascript/ql/test/library-tests/PropWrite/getAPropertyReference.expected b/javascript/ql/test/library-tests/PropWrite/getAPropertyReference.expected
index bf832301b9b4..a6692956438c 100644
--- a/javascript/ql/test/library-tests/PropWrite/getAPropertyReference.expected
+++ b/javascript/ql/test/library-tests/PropWrite/getAPropertyReference.expected
@@ -1,5 +1,7 @@
 | classes.ts:3:21:3:20 | this | classes.ts:4:3:4:24 | instanc ...  foo(); |
 | classes.ts:8:3:8:2 | this | classes.ts:8:15:8:35 | public  ... erField |
+| classes.ts:12:5:12:4 | this | classes.ts:12:17:12:37 | public  ... erField |
+| classes.ts:16:5:16:4 | this | classes.ts:16:17:16:37 | public  ... erField |
 | tst.js:1:1:1:0 | this | tst.js:23:15:23:29 | this.someMethod |
 | tst.js:1:1:1:0 | this | tst.js:24:36:24:45 | this.state |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | tst.js:3:5:3:8 | x: 4 |
diff --git a/javascript/ql/test/library-tests/PropWrite/getAPropertyReference2.expected b/javascript/ql/test/library-tests/PropWrite/getAPropertyReference2.expected
index 55c3bb6ea681..8bf36ce9ae77 100644
--- a/javascript/ql/test/library-tests/PropWrite/getAPropertyReference2.expected
+++ b/javascript/ql/test/library-tests/PropWrite/getAPropertyReference2.expected
@@ -1,5 +1,7 @@
 | classes.ts:3:21:3:20 | this | instanceField | classes.ts:4:3:4:24 | instanc ...  foo(); |
 | classes.ts:8:3:8:2 | this | parameterField | classes.ts:8:15:8:35 | public  ... erField |
+| classes.ts:12:5:12:4 | this | parameterField | classes.ts:12:17:12:37 | public  ... erField |
+| classes.ts:16:5:16:4 | this | parameterField | classes.ts:16:17:16:37 | public  ... erField |
 | tst.js:1:1:1:0 | this | someMethod | tst.js:23:15:23:29 | this.someMethod |
 | tst.js:1:1:1:0 | this | state | tst.js:24:36:24:45 | this.state |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | f | tst.js:7:5:9:5 | f() {\\n  ... ;\\n    } |
diff --git a/javascript/ql/test/library-tests/PropWrite/getAPropertySource.expected b/javascript/ql/test/library-tests/PropWrite/getAPropertySource.expected
index 6cdb0154c11d..101dba0e8a49 100644
--- a/javascript/ql/test/library-tests/PropWrite/getAPropertySource.expected
+++ b/javascript/ql/test/library-tests/PropWrite/getAPropertySource.expected
@@ -1,5 +1,9 @@
 | classes.ts:3:21:3:20 | this | instanceField | classes.ts:4:19:4:23 | foo() |
 | classes.ts:8:3:8:2 | this | parameterField | classes.ts:8:22:8:35 | parameterField |
+| classes.ts:12:5:12:4 | this | parameterField | classes.ts:12:24:12:37 | parameterField |
+| classes.ts:12:5:12:4 | this | parameterField | classes.ts:12:41:12:42 | {} |
+| classes.ts:16:5:16:4 | this | parameterField | classes.ts:16:24:16:37 | parameterField |
+| classes.ts:16:5:16:4 | this | parameterField | classes.ts:16:41:16:42 | {} |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | f | tst.js:7:6:9:5 | () {\\n   ... ;\\n    } |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | func | tst.js:4:11:6:5 | functio ... ;\\n    } |
 | tst.js:12:1:19:1 | class C ... ;\\n  }\\n} | func | tst.js:13:14:15:3 | (x) {\\n  ... x);\\n  } |
diff --git a/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite.expected b/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite.expected
index 39344ef11d7b..485beb857984 100644
--- a/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite.expected
+++ b/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite.expected
@@ -1,5 +1,7 @@
 | classes.ts:3:21:3:20 | this | classes.ts:4:3:4:24 | instanc ...  foo(); |
 | classes.ts:8:3:8:2 | this | classes.ts:8:15:8:35 | public  ... erField |
+| classes.ts:12:5:12:4 | this | classes.ts:12:17:12:37 | public  ... erField |
+| classes.ts:16:5:16:4 | this | classes.ts:16:17:16:37 | public  ... erField |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | tst.js:3:5:3:8 | x: 4 |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | tst.js:4:5:6:5 | func: f ... ;\\n    } |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | tst.js:7:5:9:5 | f() {\\n  ... ;\\n    } |
diff --git a/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite2.expected b/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite2.expected
index 4e38837a447b..e276e476ec83 100644
--- a/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite2.expected
+++ b/javascript/ql/test/library-tests/PropWrite/getAPropertyWrite2.expected
@@ -1,5 +1,7 @@
 | classes.ts:3:21:3:20 | this | instanceField | classes.ts:4:3:4:24 | instanc ...  foo(); |
 | classes.ts:8:3:8:2 | this | parameterField | classes.ts:8:15:8:35 | public  ... erField |
+| classes.ts:12:5:12:4 | this | parameterField | classes.ts:12:17:12:37 | public  ... erField |
+| classes.ts:16:5:16:4 | this | parameterField | classes.ts:16:17:16:37 | public  ... erField |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | f | tst.js:7:5:9:5 | f() {\\n  ... ;\\n    } |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | func | tst.js:4:5:6:5 | func: f ... ;\\n    } |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | x | tst.js:3:5:3:8 | x: 4 |
diff --git a/javascript/ql/test/library-tests/PropWrite/hasPropertyWrite.expected b/javascript/ql/test/library-tests/PropWrite/hasPropertyWrite.expected
index b4d999ab9a29..e6138ec0a33d 100644
--- a/javascript/ql/test/library-tests/PropWrite/hasPropertyWrite.expected
+++ b/javascript/ql/test/library-tests/PropWrite/hasPropertyWrite.expected
@@ -1,5 +1,8 @@
 | classes.ts:3:21:3:20 | this | instanceField | classes.ts:4:19:4:23 | foo() |
 | classes.ts:8:3:8:2 | this | parameterField | classes.ts:8:22:8:35 | parameterField |
+| classes.ts:12:5:12:4 | this | parameterField | classes.ts:12:24:12:37 | parameterField |
+| classes.ts:16:5:16:4 | this | parameterField | classes.ts:16:24:16:37 | parameterField |
+| classes.ts:16:5:16:4 | this | parameterField | classes.ts:16:41:16:42 | {} |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | f | tst.js:7:6:9:5 | () {\\n   ... ;\\n    } |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | func | tst.js:4:11:6:5 | functio ... ;\\n    } |
 | tst.js:2:11:10:1 | {\\n    x ...     }\\n} | x | tst.js:3:8:3:8 | 4 |
diff --git a/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/CallWithAnalyzedReturnFlow.expected b/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/CallWithAnalyzedReturnFlow.expected
index ab6686a25fff..650ca382a063 100644
--- a/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/CallWithAnalyzedReturnFlow.expected
+++ b/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/CallWithAnalyzedReturnFlow.expected
@@ -7,6 +7,7 @@
 | tst.js:11:5:11:8 | f1() | file://:0:0:0:0 | undefined |
 | tst.js:14:5:14:8 | f2() | file://:0:0:0:0 | undefined |
 | tst.js:15:5:15:8 | f2() | file://:0:0:0:0 | undefined |
+| tst.js:18:5:18:11 | o1.f3() | file://:0:0:0:0 | undefined |
 | tst.js:23:5:23:8 | f4() | tst.js:21:16:21:30 | function f5 |
 | tst.js:23:5:23:10 | f4()() | file://:0:0:0:0 | undefined |
 | tst.js:30:5:30:8 | f6() | tst.js:26:16:28:9 | function f7 |
diff --git a/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/InvokeNodeValue.expected b/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/InvokeNodeValue.expected
index 85b74fa0d7ed..a3a83471adab 100644
--- a/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/InvokeNodeValue.expected
+++ b/javascript/ql/test/library-tests/TypeInference/CallWithAnalyzedReturnFlow/InvokeNodeValue.expected
@@ -11,7 +11,7 @@
 | tst.js:11:5:11:8 | f1() | file://:0:0:0:0 | undefined |
 | tst.js:14:5:14:8 | f2() | file://:0:0:0:0 | undefined |
 | tst.js:15:5:15:8 | f2() | file://:0:0:0:0 | undefined |
-| tst.js:18:5:18:11 | o1.f3() | file://:0:0:0:0 | indefinite value (call) |
+| tst.js:18:5:18:11 | o1.f3() | file://:0:0:0:0 | undefined |
 | tst.js:23:5:23:8 | f4() | tst.js:21:16:21:30 | function f5 |
 | tst.js:23:5:23:10 | f4()() | file://:0:0:0:0 | undefined |
 | tst.js:30:5:30:8 | f6() | tst.js:26:16:28:9 | function f7 |
diff --git a/javascript/ql/test/query-tests/Declarations/UnusedProperty/UnusedProperty.expected b/javascript/ql/test/query-tests/Declarations/UnusedProperty/UnusedProperty.expected
new file mode 100644
index 000000000000..a6caa794c224
--- /dev/null
+++ b/javascript/ql/test/query-tests/Declarations/UnusedProperty/UnusedProperty.expected
@@ -0,0 +1,9 @@
+| tst.js:4:9:4:19 | unused1: 42 | Unused property unused1. |
+| tst.js:19:5:19:15 | unused9: 42 | Unused property unused9. |
+| tst.js:26:13:26:24 | unused11: 42 | Unused property unused11. |
+| tst.js:31:13:31:35 | used12_ ... lly: 42 | Unused property used12_butNotReally. |
+| tst.js:32:13:32:24 | unused12: 42 | Unused property unused12. |
+| tst.js:52:3:52:14 | unused14: 42 | Unused property unused14. |
+| tst.js:54:2:54:17 | local14.unused14 | Unused property unused14. |
+| tst.js:55:2:55:17 | local14.unused14 | Unused property unused14. |
+| tst.ts:24:21:24:25 | p: 42 | Unused property p. |
diff --git a/javascript/ql/test/query-tests/Declarations/UnusedProperty/UnusedProperty.qlref b/javascript/ql/test/query-tests/Declarations/UnusedProperty/UnusedProperty.qlref
new file mode 100644
index 000000000000..9583241c2f0d
--- /dev/null
+++ b/javascript/ql/test/query-tests/Declarations/UnusedProperty/UnusedProperty.qlref
@@ -0,0 +1 @@
+Declarations/UnusedProperty.ql
diff --git a/javascript/ql/test/query-tests/Declarations/UnusedProperty/tst.js b/javascript/ql/test/query-tests/Declarations/UnusedProperty/tst.js
new file mode 100644
index 000000000000..5bdc95a49df9
--- /dev/null
+++ b/javascript/ql/test/query-tests/Declarations/UnusedProperty/tst.js
@@ -0,0 +1,83 @@
+(function(){
+    var local1 = {
+        used1: 42,
+        unused1: 42
+    };
+    local1.used1;
+
+    var unused2 = {
+        unused2a: 42,
+        unused2b: 42
+    };
+
+    for (x.p in { used3: 42 });
+    for (x.p of { used4: 42 });
+    42 in { used5: 42 };
+    f(...{used6: 42});
+    [...{used7: 42}];
+	({...{used8: 42}});
+	({ unused9: 42 }) + "";
+    ({ used10: 42 }).hasOwnProperty;
+    ({ used10: 42 }).propertyIsEnumerable;
+
+    (function(){
+        var local11 = {
+            used11: 42,
+            unused11: 42
+        };
+        local11.used11;
+
+        var local12 = {
+            used12_butNotReally: 42,
+            unused12: 42
+        };
+
+        throw x;
+
+        local12.used12_butNotReally;
+
+        var local13 = {
+            used13: 42,
+            unused13: 42
+        };
+        local13.used13;
+    });
+    (function(options){
+        if(unknown)
+            options = {};
+        options.output = 42;
+    });
+
+	var local14 = {
+		unused14: 42
+	};
+	local14.unused14 = 42;
+	local14.unused14 = 42;
+
+
+	var local15 = {
+		semiUnused15: 42
+	};
+	local15.semiUnused15 = 42;
+	local15.semiUnused15;
+});
+(function(unusedParam = {unusedProp: 42}){
+
+});
+(function(){
+	var unusedObj = {
+		unusedProp: 42
+	};
+});
+(function(){
+	var unusedSpecials = {
+		toString: function(){},
+		valueOf: function(){},
+		'@@iterator': function(){}
+	};
+	unusedSpecials.foo;
+});
+
+(function(){
+	({ unusedProp: 42 }, 42);
+});
diff --git a/javascript/ql/test/query-tests/Declarations/UnusedProperty/tst.ts b/javascript/ql/test/query-tests/Declarations/UnusedProperty/tst.ts
new file mode 100644
index 000000000000..7ad7c508df8d
--- /dev/null
+++ b/javascript/ql/test/query-tests/Declarations/UnusedProperty/tst.ts
@@ -0,0 +1,28 @@
+(function(){
+    var o1: { p: int, q: int } = { p: 42, q: 42 };
+    o1.q;
+
+    var o2 = <{ p: int, q: int }>{ p: 42, q: 42 };
+    o2.q;
+
+    var o3: { p: int, q: int } = f();
+    o3 = o3 || { p: 42, q: 42 };
+    o3.q;
+
+});
+
+class C {
+    private o: { p: int, q: int };
+
+    constructor() {
+        this.o = { p: 42, q: 42 };
+        this.o.q;
+    }
+}
+
+(function(){
+    var o1: any = { p: 42, q: 42 };
+    o1.q;
+    var o2: any = { p: 42, q: 42 };
+    var o3: { p: int, q: int } = o2;
+})
diff --git a/javascript/ql/test/query-tests/Declarations/UnusedVariable/dead.js b/javascript/ql/test/query-tests/Declarations/UnusedVariable/dead.js
new file mode 100644
index 000000000000..10fcd168991e
--- /dev/null
+++ b/javascript/ql/test/query-tests/Declarations/UnusedVariable/dead.js
@@ -0,0 +1,4 @@
+(function(){
+	throw 42;
+	var x = 42;
+});