values()
方法返回一个新的 Array Iterator
对象,该对象包含数组每个索引的值
语法
arr.values()
返回值
一个新的 Array
迭代对象。
示例
使用 for...of
循环进行迭代
let arr = ['w', 'y', 'k', 'o', 'p']; let eArr = arr.values(); // 您的浏览器必须支持 for..of 循环 // 以及 let —— 将变量作用域限定在 for 循环中 for (let letter of eArr) { console.log(letter); }
Array.prototype.values is default implementation of Array.prototype[Symbol.iterator].
Array.prototype.values === Array.prototype[Symbol.iterator]
使用.next()迭代
var arr = ['a', 'b', 'c', 'd', 'e'];
var iterator = arr.values();
iterator.next(); // Object { value: "a", done: false }
iterator.next().value; // "b"
iterator.next()["value"]; // "c"
iterator.next(); // Object { value: "d", done: false }
iterator.next(); // Object { value: "e", done: false }
iterator.next(); // Object { value: undefined, done: true }
iteraroe.next().value; // undefined
One-use: the array iterator object is one use or temporary object
example:
var arr = ['a', 'b', 'c', 'd', 'e'];
var iterator = arr.values();
for (let letter of iterator) {
console.log(letter);
} //"a" "b" "c" "d"
for (let letter of iterator) {
console.log(letter);
} // undefined
reason: When next().done=true
or currentIndex>length
the for..of
loop end. see Iteration protocols.
Value: there is no values stored in the array Iterator object,instead its store the adresse of the array used in creation of it so its depend on the values stored on that array.
var arr = ['a', 'b', 'c', 'd', 'e'];
var iterator = arr.values();
console.log(iterator); // Array Iterator { }
iterator.next().value; // "a"
arr[1]='n';
iterator.next().value; // "n"
if the values in the array changed the array iterator object values change too
TODO: please write about why we need it, use cases.
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) Array.prototype.values |
Standard | Initial definition. |
ECMAScript Latest Draft (ECMA-262) Array.prototype.values |
Draft |
规范
规范名称 | 规范状态 | 备注 |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) Array.prototype.values |
Standard | 首次定义 |
ECMAScript Latest Draft (ECMA-262) Array.prototype.values |
Draft |
浏览器兼容性
The compatibility table in 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 | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
values |
Chrome Full support 66 | Edge Full support 12 | Firefox Full support 60 | IE No support No | Opera Full support 53 | Safari Full support 9 | WebView Android Full support 66 | Chrome Android Full support 66 | Firefox Android Full support 60 | Opera Android Full support 47 | Safari iOS Full support 9 | Samsung Internet Android Full support 9.0 | nodejs Full support 10.9.0
|
Legend
- Full support
- Full support
- No support
- No support
- See implementation notes.
- See implementation notes.
- User must explicitly enable this feature.
- User must explicitly enable this feature.