Generator

Generator函数是ES6提供的一种异步编程解决方案
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Generator 对象由生成器函数返回并且它符合可迭代协议和迭代器协议。
Generator 是隐藏类 Iterator 的子类。

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尝试一下:

const mall = function* () {
        yield 'apple'
        yield 'banana'
        yield 'cherry'
    }
     let food = ''
     for (let i of mall()) {
       food += i + ' '
     }
    console.log(food)
    

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使用next()

const mall = function* () {
        yield 'apple'
        yield 'banana'
        yield 'cherry'
    }
    // let food = ''
    // for (let i of mall()) {
    //   food += i + ' '
    // }
    // console.log(food)
    const food = mall()

此处的done表示generator函数中有没有走完yield
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使用forof

const mall = function* () {
        yield 'apple'
        yield 'banana'
        yield 'cherry'
    }
    // let food = ''
    // for (let i of mall()) {
    //   food += i + ' '
    // }
    // console.log(food)
    const food = mall()
    for (const iterator of food) {
        console.log(iterator);
    }

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异步调用

<script>
    const findCity = function* () {
        yield axios('URL?p')
        yield axios('URL?p')
    }

    const logCity = findCity()

    logCity.next().value.then(res => {
        console.log(res.data.list)
        return logCity.next().value
    }).then(res => {
        console.log(res.data.list)
    })

</script>