冒泡排序

for 循环

const arr = [3, 4, 2, 7, 9, 6, 2, 8, 3, 6, 2, 1, 6, 3, 7, 4, 21, 8, 0, 5];
var i = arr.length - 1,
    pos = 0;
var l = arr.length - 1;
while (i) {
    for (var j = 0; j < arr.length - i - 1; j++) {
        if (arr[j] > arr[j + 1]) {
            let tmp = arr[j];
            arr[j] = arr[j + 1]
            arr[j + 1] = tmp;
        }
    }
    i--;
}

console.log(arr);

while 循环

const arr = [3, 4, 2, 7, 9, 6, 2, 8, 3, 6, 2, 1, 6, 3, 7, 4, 21, 8, 0, 5];
var m = 0;
console.time('计时');
for (var j = 0; j < arr.length; j++) {
    // let flag = true;
    for (var i = 0; i < arr.length - j - 1; i++) {
        if (arr[i] > arr[i + 1]) {
            let tmp = arr[i];
            arr[i] = arr[i + 1];
            arr[i + 1] = tmp;
            m++;
        }
    }
    // if (flag) {
    //     break;
    // }
}
console.timeEnd('计时');
console.log(arr);
console.log(m);