实现Promise.all #37

zuopf769 · 2023-04-26T08:52:26Z

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    <title>Document</title>
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    <script>

        function getPromise(value, time) {
            return new Promise((r,j) => {
                setTimeout(() => {
                    r(value)
                }, time);
            });
        }

        Promise.all = function(promises) {
            // 返回一个新的promise
            return new Promise((resolve, reject) => {
                // 存储所有promise结果的数组
                let result = [];
                // 参数中的promise的个数
                let count = promises.length;
                // 计数器
                let time = 0;

                // 处理数据
                function processData(i, data) {
                    result[i] = data;
                    // 数据都处理完毕后，resolve返回结果
                    if (++time >= count) {
                        resolve(result);
                    }
                }

                // 遍历参数中传入的promises
                for (let i = 0; i < count; i++) {
                    let cur = promises[i];
                    // 处理每个promise的结果；成功就放到result中，如果有一个失败就整体失败
                    Promise.resolve(cur).then((data) => {
                        // 处理数据，因为需要记录顺序所以需要传i
                        processData(i, data);
                    }, reject);
                }

            })
        }

        let promise1 = getPromise(1, 1000);
        let promise2 = getPromise(2, 2000);
        let promise3 = getPromise(3, 3000);

        Promise.all([promise1, promise2, promise3]).then((data) => {
            console.log(data);
        })

    </script>
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实现Promise.all #37

实现Promise.all #37

zuopf769 commented Apr 26, 2023

实现Promise.all #37

实现Promise.all #37

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zuopf769 commented Apr 26, 2023