有源码不理解，

Question

各位大佬，开门见山，就下面这串源码看不太懂，求指点

var R = typeof Reflect === 'object' ? Reflect : null
var ReflectApply = R && typeof R.apply === 'function'
  ? R.apply
  : function ReflectApply(target, receiver, args) {
    return Function.prototype.apply.call(target, receiver, args);
  }

1.Reflect 这个是什么，我在vscode中打开，发现指向到一个d.ts文件
内容如下,但这个文件的出处是哪里呢？属于node吗？：

/// <reference no-default-lib="true"/>


declare namespace Reflect {
    function apply(target: Function, thisArgument: any, argumentsList: ArrayLike<any>): any;
    function construct(target: Function, argumentsList: ArrayLike<any>, newTarget?: any): any;
    function defineProperty(target: object, propertyKey: PropertyKey, attributes: PropertyDescriptor): boolean;
    function deleteProperty(target: object, propertyKey: PropertyKey): boolean;
    function get(target: object, propertyKey: PropertyKey, receiver?: any): any;
    function getOwnPropertyDescriptor(target: object, propertyKey: PropertyKey): PropertyDescriptor | undefined;
    function getPrototypeOf(target: object): object;
    function has(target: object, propertyKey: PropertyKey): boolean;
    function isExtensible(target: object): boolean;
    function ownKeys(target: object): PropertyKey[];
    function preventExtensions(target: object): boolean;
    function set(target: object, propertyKey: PropertyKey, value: any, receiver?: any): boolean;
    function setPrototypeOf(target: object, proto: any): boolean;
}

2.Function.prototype.apply.call 这个没看懂什么意思？
单独的apply和call能理解，这2个连在一起。。

Answer 1

https://developer.mozilla.org...

https://stackoverflow.com/que...