将目标元素移动到数组开头，其余元素保持原顺序的方法
functionmoveToFirst(arr,target){constindex=arr.indexOf(target);if(index!==-1){constitem=arr.splice(index,1)[0];arr.unshift(item);}returnarr;}constarr=[1,2,3];console.log(moveToFirst(arr,3));// [3, 1, 2]
functionmoveToFirst(arr,target){constindex=arr.indexOf(target);if(index!==-1){constitem=arr.splice(index,1)[0];arr.unshift(item);}returnarr;}constarr=[1,2,3];console.log(moveToFirst(arr,3));// [3, 1, 2]