Difference on call --- bind --- apply the

Directed to solve this problem:
1.call the bind-effect is the same, but different parameter passing mode, the received call parameter list, receiving a parameter array Apply.
2.bind binding returns a function that is not performed.

   Function.prototype.myCall = function (context = window) {
   context.fn = this;

  var args = [...arguments].slice(1);

  var result = context.fn(...args);
  // 执行完后干掉
  delete context.fn;
  return result;
}

Function.prototype.myApply = function (context = window) {
  context.fn = this;

  var result
  // 判断 arguments[1] 是不是 undefined
  if (arguments[1]) {
    result = context.fn(...arguments[1])
  } else {
    result = context.fn()
  }

  delete context.fn
  return result;

Function.prototype.myBind = function (context) {
  if (typeof this !== 'function') {
    throw new TypeError('Error')
  }
  var _this = this
  var args = [...arguments].slice(1)
  // 返回一个函数
  return function F() {
    // 因为返回了一个函数，我们可以 new F()，所以需要判断
    if (this instanceof F) {
      return new _this(...args, ...arguments)
    }
    return _this.apply(context, args.concat(...arguments))
  }
}

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