javascript-interview-questions-04(JS core)

Closure

Use case 1: cache data.

In the following example, the inner function getId referenced the variable id in outer function createIdGenerator. The variable id is memorized and each call to generateId will return the next id.

function createIdGenerator() {
  let id = 0;
  return function getId() {
    return id++;
  };
}

const generateId = createIdGenerator();
console.log(generateId()); // 0
console.log(generateId()); // 1
console.log(generateId()); // 2

event loop

prototype

this

this in javascript is a very complex concept, and we need a separated post to elaborate it. Here we just give a brief introduction.

promise

async/await

据说async/await底层是借助Promise和generator来实现的，有待学习。