JavaScript implements insertion sort

Ideas

Take ascending order as an example:

1. Compare from the second number forward
2. If it is smaller than the previous number, continue to compare
3. Insert the element in the right place
4. The third number starts to compare
5. And so on, proceed to the last number

The animation demonstration of ascending insertion sort is shown in the figure:

Time complexity : O(n ² )

achieve

Existing array [7, 5, 4, 15, 3, 9, 6, 12], sort in ascending order:

Array.prototype.insertionSort = function() {
    
    
    // 第一个数默认已经排序
    // 从第二个数开始，遍历没有排序过的数
    for (let i = 1; i < this.length; i++) {
    
    
        // 提取当前遍历的元素
        const temp = this[i];
        // 从当前元素位置往前比较
        let j = i;
        while (j > 0) {
    
    
            // 如果前一个数比提取的数
            if (this[j - 1] > temp) {
    
    
                // 将前一个数后移
                this[j] = this[j - 1];
            } else {
    
    
                // 否则退出循环
                break;
            }
            // 每比较一次，往前进一位
            j--;
        }
        // 遍历完成后，将提取的数插入
        this[j] = temp;
    }
};

const arr = [7, 5, 4, 15, 3, 9, 6, 12];
arr.insertionSort();
console.log(arr);

Results of the: