promise多请求并发

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8" />
    <title></title>
</head>

<body>
    <script>
        let p1 = new Promise((resolve, reject) => {
            resolve('成功了')
        })

        let p2 = new Promise((resolve, reject) => {
            resolve('success')
        })

        let p3 = Promise.reject('失败')
        let p4 = Promise.reject('失败4')

        // 这种事失败成功都会返回
        Promise.allSettled([p1, p3, p2,p4,p2])
            .then((results) => {
                /***
                 *   results是一个数组，内容如下
                 * [
                 * {status:'fulfilled',value:'成功了'},
                 * {status:'rejected',value:'失败'},
                 * {status:'fulfilled',value:'成功了'},
                 * {status:'rejected',value:'失败4'},
                 * {status:'fulfilled',value:'成功了'},
                 *
                 * ]
                */
                console.log('不管有没有成功失败，我这都会执行：', results);
                results.forEach((result) => {

                    if (result.status === 'fulfilled') {
                        console.log('成功：', result.value);
                    } else {
                        console.log('失败：', result.reason);
                    }
                });
            });

        // 这种是  只要有失败就会退出发送请求的行为
        Promise.all([p1, p3, p2,p4,p2]).then((result) => {
            console.log(result)
        }).catch((error) => {
            console.log(error)      // 失败了，打出 '失败'
        })


    </script>
</body>

</html>