Array.prototype.forEach

[Sunny-117]

// 无返回值，调用callback
Array.prototype.myForEach = function (callback) {
  if (typeof callback !== "function") {
    throw new TypeError(callback + " is not a function");
  }
  for (let i = 0; i < this.length; i++) {
    callback(this[i], i, this);
  }
};

[CwRv07]

Array.prototype._forEach = function (cb, thisBinding = globalThis) {
  // 排除回调非函数情况
  if (typeof cb !== "function") {
    throw new TypeError(`${cb} is not a function`);
  }
  // 排除this为非可迭代对象情况
  if (this == null || typeof this[Symbol.iterator] !== "function") {
    throw new TypeError(`${this} is not a iterable`);
  }
  // 将可迭代对象转换成数组
  const array = [...this];
  // 执行遍历并回调
  for (let i = 0; i < array.length; i++) {
    cb.call(thisBinding, array[i], i, this);
  }
};

[hannah-bingo]

forEach和map类似，但是forEach不返回结果

Array.prototype._forEach = function(callback, objThis) {
	if(typeof callback !== "function") {
		throw new TypeError("callback type error!")
	}
	for(let i = 0; i < this.length; i++) {
		callback.call(objThis, this[i], i, this);
	}	
}

[kangkang123269]

Array.prototype.myForEach = function(callback, thisArg) {
  if (this == null) {
    throw new TypeError("Cannot read property 'forEach' of null or undefined");
  }
  if (typeof callbackFn !== 'function') {
    throw new TypeError(callbackFn + ' is not a function');
  }
  for (let i = 0; i < this.length; i++) {
    callback.call(thisArg, this[i], i, this);
  }
};