splice

var arr = new Array(5);
arr[0] = "amy";
arr[1] = "elice";
arr[2] = "divi";
arr[3] = "lvy";
arr[4] = "marry";
arr.splice(1, 2, "willian");
console.log(arr);
//输出：amy，willian,lvy，从数组第一个位置起删除两个元素，并用新的元素“willian”代替删除的元素。