learn_example/JavaScript_Sea/apply&call.ts

/**
 * @description 模拟 apply&call
 * @date 2022-07-01
 * @article https://zhuanlan.zhihu.com/p/51259309
 */

function getGlobalObject() {
  return this;
}

(Function as any).prototype.myApply = function apply(
  thisArg = getGlobalObject(),
  argsArray = []
) {
  if (typeof this !== "function") {
    throw new TypeError(this + " is not a function");
  }

  if (argsArray !== new Object(argsArray)) {
    throw new TypeError("CreateListFromArrayLike called on non-object");
  }

  if (thisArg == null) thisArg = getGlobalObject();
  if (argsArray == null) argsArray = [];

  thisArg = new Object(thisArg);
  thisArg["__fn"] = this;
  const result = thisArg["__fn"](...argsArray);
  delete thisArg["__fn"];

  return result;
};

// 额外情况
// 1. 如果 thisArg 中已经存在一个同名 __fn 属性呢？
// 2. 解决以上问题不允许使用 Sybmol

(Function as any).prototype.myCall = function call(thisArg) {
  const argsArray: any[] = [];
  for (let index = 1; index <= arguments.length - 1; index++) {
    argsArray[index - 1] = arguments[index];
  }

  return this.myApply(thisArg, argsArray);
};

const testObj = {
  name: "Hello",
  child: 200,
  index: 0,
};

function tsetFunction(...args) {
  console.log("value", args);
  console.log("name", this.name);
  console.log("child", this.child);
  console.log("index", this.index);
}

(tsetFunction as any).myCall(testObj, 100, 200, 300, 400, 500, 600, 700);