题目描述

请实现Array.map函数的功能且该新函数命名为_map

测试用例

function c() {
  const a = [1, 2, 3];
  const newa = a._map((i) => i * 3);
  judge = JSON.stringify(newa) === "[3,6,9]";
  return judge;
}

输出：true

代码实现

Array.prototype._map = function(cb){
  console.log(Object.prototype.toString.call(cb));
  if(Object.prototype.toString.call(cb) !== "[object Function]"){
    return -1;
  }
  let arr = this;
  for(let i = 0; i < arr.length; i ++){
      arr[i] = cb(arr[i], i, arr);
  }
  
  return arr;
}

function test() {
  const a = [1, 2, 3];
  const newa = a._map((i) => i * 3);
  judge = JSON.stringify(newa) === "[3,6,9]";
  return judge;
}

console.log(test());
// true