`WebAssembly`JavaScript 对象是所有 WebAssembly 相关功能的命名空间。

和大多数全局对象不一样，`WebAssembly`不是一个构造函数（它不是一个函数对象）。它类似于 `Math` 对象或者 `Intl` 对象，Math 对象也是一个命名空间对象，用于保存数学常量和函数；Intl则是用于国际化和其他语言相关函数的命名空间对象。

## 描述

`WebAssembly`对象主要用于：

- 使用 `WebAssembly.instantiate()` 函数加载 WebAssembly 代码。
- 通过 `WebAssembly.Memory()`/`WebAssembly.Table()` 构造函数创建新的内存和表实例。
- 由 `WebAssembly.CompileError()`/`WebAssembly.LinkError()`/`WebAssembly.RuntimeError()` 构造函数来提供 WebAssembly 中的错误信息。

## 方法

`WebAssembly.instantiate()`
  用于编译和实例化 WebAssembly 代码的主 API，返回一个 Module 和它的第一个实例。
`WebAssembly.instantiateStreaming()`
  直接从流式底层源编译和实例化WebAssembly模块，同时返回`Module`及其第一个实例。
`WebAssembly.compile()`
  把 WebAssembly 二进制代码编译为一个 `WebAssembly.Module` ，不进行实例化。
`WebAssembly.compileStreaming()`
  直接从流式底层源代码编译`WebAssembly.Module` ，将实例化作为一个单独的步骤。
`WebAssembly.validate()`
  校验 WebAssembly 二进制代码的类型数组是否合法，合法则返回 true ，否则返回 false 。

## 构造器

`WebAssembly.Module()`
  创建一个新的WebAssembly模块对象。
`WebAssembly.Instance()`
  创建一个新的WebAssembly实例对象。
`WebAssembly.Memory()`
  创建一个新的WebAssembly内存对象。
`WebAssembly.Table()`
  创建一个新的WebAssembly表格对象。
`WebAssembly.CompileError()`
  创建一个新的WebAssembly编译错误对象。
`WebAssembly.LinkError()`
  创建一个新的WebAssembly链接错误对象。
`WebAssembly.RuntimeError()`
  创建一个新的WebAssembly运行时错误对象。

## 示例

通过fetch方法获取了WebAssembly字节码后，我们通过`WebAssembly.instantiate()`方法对模块进行编译和实例化，在这过程中将一个JavaScript 函数导入WebAssembly模块。这个promise实例解析成一个对象(result)，result包含编译了的`Module`和`Instance`对象。接下来我们调用一个Instance导出的WebAssembly方法。

    var importObject = {
      imports: {
        imported_func: function(arg) {
          console.log(arg);
        }
      }
    };

    fetch('simple.wasm').then(response =>
      response.arrayBuffer()
    ).then(bytes =>
      WebAssembly.instantiate(bytes, importObject)
    ).then(result =>
      result.instance.exports.exported_func()
    );

注意：有关使用了我们 `fetchAndInstantiate()` 库函数的示例，请查看Github上的 index.html (或者查看在线示例) 。

## 规范

Specification | Status | Comment
--- | --- | ---
WebAssembly JavaScript Interface WebAssembly | Working Draft | 初始草案定义

## 浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

| Desktop | Mobile | Server
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | Safari on iOS | Samsung Internet | Node.js
`WebAssembly` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`CompileError` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`Global` | Chrome Full support 69 | Edge No support No | Firefox Full support 62 | IE No support No | Opera No support No | Safari No support No | WebView Android Full support 69 | Chrome Android Full support 69 | Edge Mobile No support No | Firefox Android Full support 62 | Opera Android No support No | Safari iOS No support No | Samsung Internet Android No support No | nodejs No support No
`Instance` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`LinkError` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`Memory` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`Module` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`RuntimeError` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`Table` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`compile` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 Full support 44 | Safari iOS Full support 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`compileStreaming` | Chrome Full support 61 | Edge Full support 16 | Firefox Full support 58 | IE No support No | Opera Full support 47 | Safari No support No | WebView Android Full support 61 | Chrome Android Full support 61 | Edge Mobile No support No | Firefox Android Full support 58 | Opera Android ? | Safari iOS No support No | Samsung Internet Android No support No | nodejs No support No
`instantiate` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs Full support 8.0.0
`instantiateStreaming` | Chrome Full support 61 | Edge Full support 16 | Firefox Full support 58 | IE No support No | Opera Full support 47 | Safari No support No | WebView Android Full support 61 | Chrome Android Full support 61 | Edge Mobile No support No | Firefox Android Full support 58 | Opera Android ? | Safari iOS No support No | Samsung Internet Android No support No | nodejs No support No
`validate` | Chrome Full support 57 | Edge Full support 16 | Firefox Full support 52 Notes Full support 52 Notes Notes Disabled in the Firefox 52 Extended Support Release (ESR). | IE No support No | Opera Full support 44 | Safari Full support 11 | WebView Android Full support 57 | Chrome Android Full support 57 | Edge 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 11 | Samsung Internet Android Full support 7.0 | nodejs 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.

## 参见

- WebAssembly overview page
- WebAssembly concepts
- Using the WebAssembly JavaScript API