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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

next() method returns an object with two properties done and value . You can also provide a parameter to the next method to send a value to the generator.

句法

gen.next(value)
					

参数

value

The value to send to the generator.

The value will be assigned as a result of a yield expression. For example, in variable = yield expression , the value passed to the .next() function will be assigned to variable .

返回值

Object with two properties:

done (boolean)

Has the value true if the iterator is past the end of the iterated sequence. In this case value optionally specifies the 返回值 of the iterator.

Has the value false if the iterator was able to produce the next value in the sequence. This is equivalent of not specifying the done property altogether.

value

Any JavaScript value returned by the iterator. Can be omitted when done is true .

范例

Using next()

The following example shows a simple generator and the object that the next method returns:

function* gen() {
  yield 1;
  yield 2;
  yield 3;
}
const g = gen(); // "Generator { }"
g.next();      // "Object { value: 1, done: false }"
g.next();      // "Object { value: 2, done: false }"
g.next();      // "Object { value: 3, done: false }"
g.next();      // "Object { value: undefined, done: true }"
						

Using next() with a list

function* getPage(pageSize = 1, list) {
  let output = [];
  let index = 0;
  while (index < list.length) {
    output = [];
    for (let i = index; i < index + pageSize; i++) {
      if (list[i]) {
        output.push(list[i]);
      }
    }
    yield output;
    index += pageSize;
  }
}
list = [1, 2, 3, 4, 5, 6, 7, 8]
var page = getPage(3, list);              // Generator { }
page.next();                              // Object {value: (3) [1, 2, 3], done: false}
page.next();                              // Object {value: (3) [4, 5, 6], done: false}
page.next();                              // Object {value: (2) [7, 8], done: false}
page.next();                              // Object {value: undefined, done: true}
						

Sending values to the generator

在此范例中， next is called with a value.

Note that the first call does not log anything, because the generator was not yielding anything initially.

function* gen() {
  while (true) {
    let value = yield null;
    console.log(value);
  }
}
const g = gen();
g.next(1);
// "{ value: null, done: false }"
g.next(2);
// 2
// "{ value: null, done: false }"
						

规范

规范
ECMAScript (ECMA-262) The definition of 'Generator.prototype.next' 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
next	Chrome 39	Edge 13	Firefox 26	IE No	Opera 26	Safari 10	WebView Android 39	Chrome Android 39	Firefox Android 26	Opera Android 26	Safari iOS 10	Samsung Internet Android 4.0	nodejs Yes

图例

完整支持

完整支持

不支持

不支持

另请参阅

• function*
• 迭代器和生成器

元数据

• 最后修改： Aug 7, 2020

相关话题

1. 标准内置对象
2. Generator
3. 方法
   1. Generator.prototype.next()
   2. Generator.prototype.return()
   3. Generator.prototype.throw()
4. 继承：
5. Function
6. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
7. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
8. Object
9. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
10. 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()