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:
{
"totalJSHeapSize": 39973671,
"usedJSHeapSize": 39127515,
"jsHeapSizeLimit": 4294705152
}
Specifications
None.