The content of this article is to explain the code examples of the Iterator interface in ES6. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

In es6, when operating certain data structures (array object map set), how to use a unified method to operate? The Iterator interface implements such a function

1 .Application of Iterator in array

{
    let arr = ['hello', 'world'];
    // 数组内部实现了iterator接口，所以直接调用[Symbol.iterator]()
    let map = arr[Symbol.iterator]();
    console.log(map.next()); // {value: "hello", done: false}
    console.log(map.next()); // {value: "world", done: false}
    console.log(map.next()); // {value: undefined, done: true}
    // value 表示数组元素，done表示循环是否有下一步状态，true:没有下一步了，false:循环没有结束
}

2. Customized Iterator interface

{
    // object没有内置iterator接口，自定义iterator接口，让obj也可以使用for...of
    let obj = {
        start: [1,2,3],
        end: [4,5,6],
        // 声明iterator接口方法
        [Symbol.iterator]() {
            // 先遍历start，再遍历end
            let arr = this.start.concat(this.end);
            let index = 0;
            // 返回next()
            return {
                next() {
                    if (index <p><strong>3.for...of loop</strong> </p><pre class="brush:php;toolbar:false">{
    // 数组内部实现了iterator接口，所以可以直接使用for...of循环
    let arr = ['hello', 'world'];
    for (let value of arr) {
        console.log(value); // hello world
    }
}

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In es6, when operating certain data structures (array object map set), how to operate in a unified method? The Iterator interface implements such a function1. Application of Iterator in arrays

{
    let arr = ['hello', 'world'];
    // 数组内部实现了iterator接口，所以直接调用[Symbol.iterator]()
    let map = arr[Symbol.iterator]();
    console.log(map.next()); // {value: "hello", done: false}
    console.log(map.next()); // {value: "world", done: false}
    console.log(map.next()); // {value: undefined, done: true}
    // value 表示数组元素，done表示循环是否有下一步状态，true:没有下一步了，false:循环没有结束
}

{
    // object没有内置iterator接口，自定义iterator接口，让obj也可以使用for...of
    let obj = {
        start: [1,2,3],
        end: [4,5,6],
        // 声明iterator接口方法
        [Symbol.iterator]() {
            // 先遍历start，再遍历end
            let arr = this.start.concat(this.end);
            let index = 0;
            // 返回next()
            return {
                next() {
                    if (index <p class="article fmt article__content"><br>3.for.. .of loop</p><p></p><pre class="brush:php;toolbar:false">{
    // 数组内部实现了iterator接口，所以可以直接使用for...of循环
    let arr = ['hello', 'world'];
    for (let value of arr) {
        console.log(value); // hello world
    }
}

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