function insertionSort (arr) {
let n = arr.length;
let preIndex, current;
for (let i = 1; i < n; i++) {
current = arr[i];
preIndex = i - 1;
// 如果前面的比当前的大就向后挪
while (preIndex >= 0 && arr[preIndex] > current) {
arr[preIndex + 1] = arr[preIndex];
preIndex--;
}
// 当前的挪到空出来的位置
arr[preIndex + 1] = current;
}
return arr;
}
var arr = insertionSort([3, 2, 4, 5, 1]);
console.log(arr);