编辑代码

Array.prototype.remove=function(obj){
    var index=this.indexOf(obj);
    if(index>-1){
        this.splice(index,1);
    }
}
let arr=['a','b','c','d','e','f','g']
console.log(arr)
// arr.remove("a")
// console.log(arr)
arr.copyWithin(2,1,3)
console.log(arr)