indexOf & lastIndexOf
Array.prototype.myIndexOf = function(ele,start = 0){ for(let i = start;i < this.length;i++){ let item = this[i] if(ele === item){ return i } } return -1 }
Array.prototype.myLastIndexOf = function(ele,start = this.length - 1){ for(let i = start;i > -1;i--){ let item = this[i] if(ele === item){ return i } } return -1 }
以自己现在的努力程度,还没有资格和别人拼天赋