Feat/async function

javascript-stringify.js

@@ -91,6 +91,16 @@
     return fn.constructor.name === 'GeneratorFunction';
   }
 
+  /**
+   * Check if a function is an ES7 async function
+   *
+   * @param  {Function} fn
+   * @return {boolean}
+   */
+  function isAsyncFunction (fn) {
+    return fn.constructor.name === 'AsyncFunction';
+  }
+
   /**
    * Can be replaced with `str.startsWith(prefix)` if code is updated to ES6.
    *
@@ -281,7 +291,7 @@
     if (indent) {
       value = dedentFunction(value);
     }
-    var prefix = isGeneratorFunction(fn) ? '*' : '';
+    var prefix = isGeneratorFunction(fn) ? '*' : isAsyncFunction(fn) ? 'async ' : '';
     if (fn.name && stringStartsWith(value, prefix + fn.name + '(')) {
       // Method notation was used to define this function, but it was transplanted from another object.
       // Convert to regular function notation.
@@ -320,6 +330,7 @@
     '[object RegExp]': String,
     '[object Function]': stringifyFunction,
     '[object GeneratorFunction]': stringifyFunction,
+    '[object AsyncFunction]': stringifyFunction,
     '[object global]': toGlobalVariable,
     '[object Window]': toGlobalVariable
   };

test.js

@@ -207,6 +207,10 @@ describe('javascript-stringify', function () {
           it('should stringify', testRoundTrip('function* (x) { yield x; }'));
         });
 
+        describe('async', function () {
+          it('should stringify', testRoundTrip('async function (x) { await x; }'));
+        });
+
         describe('method notation', function () {
           it('should stringify', testRoundTrip('{a(b, c) { return b + c; }}'));
 
@@ -222,6 +226,11 @@ describe('javascript-stringify', function () {
             testRoundTrip("{*'function a'(b, c) { return b + c; }}")
           );
 
+          it(
+            'should not be fooled by tricky async names',
+            testRoundTrip("{async 'function a'(b, c) { return b + c; }}")
+          );
+
           it(
             'should not be fooled by empty names',
             testRoundTrip("{''(b, c) { return b + c; }}")