Performance: memory property

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.

The non-standard and legacy memory read-only property returns the size of the JavaScript heap which can be helpful to measure and reduce the memory footprint of websites.

Note that the information this API provides is unreliable as it might overestimate actual memory usage if web pages share the same heap, or might underestimate actual memory usage if web pages use workers and/or cross-site iframes that are allocated in separate heaps. It is not standardized what "heap" means exactly. The API is only available in Chromium-based browsers.

A new API aiming to replace performance.memory is Performance.measureUserAgentSpecificMemory(). It tries to estimate the memory used by a web page.

Value

Returns an object with the following properties:

jsHeapSizeLimit: The maximum size of the heap, in bytes, that is available to the context.
totalJSHeapSize: The total allocated heap size, in bytes.
usedJSHeapSize: The currently active segment of JS heap, in bytes.

Examples

Getting JavaScript heap sizes

Calling performance.memory returns an object like this:

json

{
  "totalJSHeapSize": 39973671,
  "usedJSHeapSize": 39127515,
  "jsHeapSizeLimit": 4294705152
}

Specifications

None.

Browser compatibility

	desktop					mobile							server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS	Deno	Node.js
`memory` Deprecated Non-standard	Chrome – Full support Chrome 7 (Release date: 2010-10-19) footnote Full support	Edge – Full support Edge 79 (Release date: 2020-01-15) footnote Full support	Firefox – No support Firefox footnote No support	Opera – Full support Opera 15 (Release date: 2013-07-02) footnote Full support	Safari – No support Safari footnote No support	Chrome Android – Full support Chrome Android 18 (Release date: 2012-06-27) footnote Full support	Firefox for Android – No support Firefox for Android footnote No support	Opera Android – Full support Opera Android 14 (Release date: 2013-05-21) footnote Full support	Safari on iOS – No support Safari on iOS footnote No support	Samsung Internet – Full support Samsung Internet 1 (Release date: 2013-04-27) footnote Full support	WebView Android – Full support WebView Android 4.4 (Release date: 2013-12-09) footnote Full support	WebView on iOS – No support WebView on iOS footnote No support	Deno – No support Deno footnote No support	Node.js – No support Node.js footnote No support

Tip: you can click/tap on a cell for more information.

Full support: Full support
No support: No support
: Non-standard. Check cross-browser support before using.
: Deprecated. Not for use in new websites.