在此页

• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

A WebAssembly.Global() 构造函数创建新 Global object representing a global variable instance, accessible from both JavaScript and importable/exportable across one or more WebAssembly.Module instances. This allows dynamic linking of multiple modules.

句法

new WebAssembly.Global(descriptor, value);
					

参数

descriptor

A GlobalDescriptor dictionary object, which contains two properties:

• value : A USVString representing the data type of the global. This can be one of i32 , i64 , f32 ，和 f64 .
• 可变 : A boolean value that determines whether the global is mutable or not. By default, this is false .

value

The value the variable contains. This can be any value, as long as its type matches the variable's data type. If no value is specified, a typed 0 value is used, as specified by the DefaultValue algorithm .

范例

Creating a new Global instance

The following example shows a new global instance being created using the WebAssembly.Global() constructor. It is being defined as a mutable i32 type, with a value of 0.

The value of the global is then changed, first to 42 使用 Global.value property, and then to 43 using the incGlobal() function exported out of the global.wasm module (this adds 1 to whatever value is given to it and then returns the new value).

const output = document.getElementById('output');
function assertEq(msg, got, expected) {
    output.innerHTML += `Testing ${msg}: `;
    if (got !== expected)
        output.innerHTML += `FAIL!<br>Got: ${got}<br>Expected: ${expected}<br>`;
    else
        output.innerHTML += `SUCCESS! Got: ${got}<br>`;
}
assertEq("WebAssembly.Global exists", typeof WebAssembly.Global, "function");
const global = new WebAssembly.Global({value:'i32', mutable:true}, 0);
WebAssembly.instantiateStreaming(fetch('global.wasm'), { js: { global } })
.then(({instance}) => {
    assertEq("getting initial value from wasm", instance.exports.getGlobal(), 0);
    global.value = 42;
    assertEq("getting JS-updated value from wasm", instance.exports.getGlobal(), 42);
    instance.exports.incGlobal();
    assertEq("getting wasm-updated value from JS", global.value, 43);
});
					

注意 : You can see the example running live on GitHub ; see also the source code .

规范

规范
WebAssembly JavaScript 接口 The definition of 'WebAssembly.Global() constructor' in that specification.

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. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
Global() 构造函数	Chrome 69	Edge No	Firefox 62	IE No	Opera No	Safari No	WebView Android 69	Chrome Android 69	Firefox Android 62	Opera Android No	Safari iOS No	Samsung Internet Android 10.0	nodejs No

图例

完整支持

完整支持

不支持

不支持

另请参阅

• WebAssembly 概述页面
• WebAssembly 概念
• 使用 WebAssembly JavaScript API
• Import/Export mutable globals proposal

元数据

• 最后修改： May 7, 2020

相关话题

1. 标准内置对象
2. WebAssembly
3. 方法
   1. WebAssembly.compile()
   2. WebAssembly.compileStreaming()
   3. WebAssembly.instantiate()
   4. WebAssembly.instantiateStreaming()
   5. WebAssembly.validate()
4. 相关页面：
5. WebAssembly.Module
6. WebAssembly.Global
7. WebAssembly.Instance
8. WebAssembly.Memory
9. WebAssembly.Table
10. WebAssembly.CompileError
11. WebAssembly.LinkError
12. WebAssembly.RuntimeError
13. 继承：
14. Object
15. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
16. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()