perf: add toJSON to performance class

doc/api/perf_hooks.md

@@ -261,6 +261,14 @@ If the wrapped function returns a promise, a finally handler will be attached
 to the promise and the duration will be reported once the finally handler is
 invoked.
 
+### `performance.toJSON()`
+<!-- YAML
+added: REPLACEME
+-->
+
+An object which is JSON representation of the `performance` object. It
+is similar to [`window.performance.toJSON`][] in browsers.
+
 ## Class: `PerformanceEntry`
 <!-- YAML
 added: v8.5.0
@@ -1025,4 +1033,5 @@ require('some-module');
 [`child_process.spawnSync()`]: child_process.md#child_process_child_process_spawnsync_command_args_options
 [`process.hrtime()`]: process.md#process_process_hrtime_time
 [`timeOrigin`]: https://w3c.github.io/hr-time/#dom-performance-timeorigin
+[`window.performance.toJSON`]: https://developer.mozilla.org/en-US/docs/Web/API/Performance/toJSON
 [`window.performance`]: https://developer.mozilla.org/en-US/docs/Web/API/Window/performance

lib/perf_hooks.js

@@ -59,6 +59,15 @@ class Performance extends EventTarget {
       timeOrigin: this.timeOrigin,
     }, opts)}`;
   }
+
+}
+
+function toJSON() {
+  return {
+    nodeTiming: this.nodeTiming,
+    timeOrigin: this.timeOrigin,
+    eventLoopUtilization: this.eventLoopUtilization()
+  };
 }
 
 class InternalPerformance extends EventTarget {}
@@ -105,6 +114,11 @@ ObjectDefineProperties(Performance.prototype, {
     configurable: true,
     enumerable: true,
     value: timeOriginTimestamp,
+  },
+  toJSON: {
+    configurable: true,
+    enumerable: true,
+    value: toJSON,
   }
 });
 

test/parallel/test-tojson-perf_hooks.js

@@ -0,0 +1,14 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const { performance } = require('perf_hooks');
+
+// Test toJSON for performance object
+{
+  assert.strictEqual(typeof performance.toJSON, 'function');
+  const jsonObject = performance.toJSON();
+  assert.strictEqual(typeof jsonObject, 'object');
+  assert.strictEqual(jsonObject.timeOrigin, performance.timeOrigin);
+  assert.strictEqual(typeof jsonObject.nodeTiming, 'object');
+}