01- Built-in objects

/ /! Built-in objects
(() = > {
  / /? 1. ECMAScript built-in objects
  let b: Boolean = new Boolean(1);
  let n: Number = new Number(true);
  let s: String = new String("abc");
  let d: Date = new Date(a);let r: RegExp = / / ^ 1;
  let e: Error = new Error("error message");
  b = true;
  // let bb: boolean = new Boolean(2) // error
  / /? 2. Built-in objects for BOM and DOM
  const div: HTMLElement | null = document.getElementById("test");
  const divs: NodeList = document.querySelectorAll("div");
  document.addEventListener("click".(event: MouseEvent) = > {
    console.dir(event.target);
  });
  const fragment: DocumentFragment = document.createDocumentFragment(); }) ();Copy the code

02- Declaration document

import jQuery from "jquery";
/ /! Introduce the third-party library JQ
//import jQuery from "jquery";

//jQuery(" selector ");

/** ** When using a third-party library, we need to reference its declaration file to obtain the corresponding code completion, interface prompts and other functions. Declare var jQuery: (selector: string) => any; var selector: (selector: string) => any; * * Declaration file: Put declaration statements in a separate file (jquery.d.ts), ts will automatically parse to all declaration files in the project * * Download declaration file: NPM install@types/jquery --save-dev
 */

jQuery("Selector");

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