handwriting-algorithm/03promise.race.html at master · ustcfury/handwriting-algorithm · GitHub

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<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        Promise.race = function (args) {
            return new Promise((resolve, rejected) => {
                for (let i = 0, n = args.length; i < n; i++) {
                    args[i].then(resolve, rejected)
                }
            })
        }
        let p1 = new Promise(function (resolve, reject) {
            setTimeout(function () {
                reject(1)
            }, 1000)
        })
        let p2 = new Promise(function (resolve, reject) {
            setTimeout(function () {
                resolve(2)
            }, 2000)
        })
        let p3 = new Promise(function (resolve, reject) {
            setTimeout(function () {
                resolve(3)
            }, 3000)
        })
        Promise.race([p3, p1, p2]).then(res => {
            console.log(res) // [3, 1, 2]
        }).catch(error => {
            console.log(error)
        })
        // p1.finally(console.log(1));
    </script>
</body>

</html>