冒泡排序

arr =[134,124,45,769,4356,3,8]

function bubble(arr){
    for(i=0;i<=arr.length-1;i++){
//每轮比较次数少1
        for(j=0;j<=arr.length-1-i;j++){
            if(arr[j]>arr[j+1]){
                let temp = arr[j+1];
                arr[j+1]=arr[j];
                arr[j]= temp;
            } 
        }
    }
    return arr;
}