我們的志工尚未將本文翻譯為 正體中文 (繁體) 版本。加入我們,幫忙翻譯!
您也可以閱讀本文的 English (US) 版本。

The WebAssembly.Memory() constructor creates a new Memory object which is a resizable ArrayBuffer that holds the raw bytes of memory accessed by a WebAssembly Instance.

A memory created by JavaScript or in WebAssembly code will be accessible and mutable from both JavaScript and WebAssembly.

Syntax

var myMemory = new WebAssembly.Memory(memoryDescriptor);

Parameters

memoryDescriptor
An object that can contain the following members:
initial
The initial size of the WebAssembly Memory, in units of WebAssembly pages.
maximum Optional
The maximum size the WebAssembly Memory is allowed to grow to, in units of WebAssembly pages.  When present, the maximum parameter acts as a hint to the engine to reserve memory up front.  However, the engine may ignore or clamp this reservation request.  In general, most WebAssembly modules shouldn't need to set a maximum.

Note: A WebAssembly page has a constant size of 65,536 bytes, i.e., 64KiB.

Exceptions

  • If memoryDescriptor is not of type object, a TypeError is thrown.
  • If maximum is specified and is smaller than initial, a RangeError is thrown.

Memory instances

All Memory instances inherit from the Memory() constructor's prototype object — this can be modified to affect all Memory instances.

Instance properties

Memory.prototype.constructor
Returns the function that created this object's instance. By default this is the WebAssembly.Memory() constructor.
Memory.prototype.buffer
An accessor property that returns the buffer contained in the memory.

Instance methods

Memory.prototype.grow()
Increases the size of the memory instance by a specified number of WebAssembly pages (each one is 64KB in size).

Examples

There are two ways to get a WebAssembly.Memory object.  The first way is to construct it from JavaScript.  The following example creates a new WebAssembly Memory instance with an initial size of 10 pages (640KiB), and a maximum size of 100 pages (6.4MiB).

var memory = new WebAssembly.Memory({initial:10, maximum:100});

The second way to get a WebAssembly.Memory object is to have it exported by a WebAssembly module.  The following example (see memory.html on GitHub, and view it live also) fetches and instantiates the loaded memory.wasm byte code using the WebAssembly.instantiateStreaming() method, while importing the memory created in the line above. It then stores some values in that memory, then exports a function and uses it to sum some values.

WebAssembly.instantiateStreaming(fetch('memory.wasm'), { js: { mem: memory } })
.then(obj => {
  var i32 = new Uint32Array(memory.buffer);
  for (var i = 0; i < 10; i++) {
    i32[i] = i;
  }
  var sum = obj.instance.exports.accumulate(0, 10);
  console.log(sum);
});

Specifications

Specification Status Comment
WebAssembly JavaScript Interface
The definition of 'Memory' in that specification.
Working Draft Initial draft definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung InternetNode.js
Basic supportChrome Full support 57Edge Full support 16Firefox Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
IE No support NoOpera Full support 44Safari Full support 11WebView Android Full support 57Chrome Android Full support 57Edge Mobile Full support Yes
Disabled
Full support Yes
Disabled
Disabled This feature is behind the Experimental JavaScript Features preference.
Firefox Android Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
Opera Android ? Safari iOS Full support 11Samsung Internet Android Full support 7.0nodejs Full support 8.0.0
bufferChrome Full support 57Edge Full support 16Firefox Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
IE No support NoOpera Full support 44Safari Full support 11WebView Android Full support 57Chrome Android Full support 57Edge Mobile Full support Yes
Disabled
Full support Yes
Disabled
Disabled This feature is behind the Experimental JavaScript Features preference.
Firefox Android Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
Opera Android ? Safari iOS Full support 11Samsung Internet Android Full support 7.0nodejs Full support 8.0.0
growChrome Full support 57Edge Full support 16Firefox Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
IE No support NoOpera Full support 44Safari Full support 11WebView Android Full support 57Chrome Android Full support 57Edge Mobile Full support Yes
Disabled
Full support Yes
Disabled
Disabled This feature is behind the Experimental JavaScript Features preference.
Firefox Android Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
Opera Android ? Safari iOS Full support 11Samsung Internet Android Full support 7.0nodejs Full support 8.0.0
prototypeChrome Full support 57Edge Full support 16Firefox Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
IE No support NoOpera Full support 44Safari Full support 11WebView Android Full support 57Chrome Android Full support 57Edge Mobile Full support Yes
Disabled
Full support Yes
Disabled
Disabled This feature is behind the Experimental JavaScript Features preference.
Firefox Android Full support 52
Notes
Full support 52
Notes
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
Opera Android ? Safari iOS Full support 11Samsung Internet Android Full support 7.0nodejs Full support 8.0.0

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.

See also

文件標籤與貢獻者

此頁面的貢獻者: chrisdavidmills, fscholz, lukewagner
最近更新: chrisdavidmills,