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Explain Event Loop

JavaScript is a single-threaded programming language. This means that JavaScript can do only one thing at a single point in time.

Inside Browser, there is a Javascript engine (we are considering V8 for chrome.) and an environment to run javascript properly. Javascript engine has two parts, Heap and Call Stack. And the engine has some assistant named Web APIs and Callback Queue.

Heaps

It's an unstructured memory block. Our code's memory allocation happens here. As a programmer we don't have to worry much about heaps.

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// callback hell

const eat = food => console.log(food)

const collectOrder = (order, cb) => {
	console.log(order)
  cb("eat rice")
}

const placeOrder = (toppings, cb) => {

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Tính tổng và tích của array sử dụng reduce javascript

function accumulation(...array) {
    return array.reduce((prev, next) => prev + next, 0);
}

function multiplication(...array) {
    return array.reduce((pre, next) => pre * next, 1);
}

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<template>
  <div class="container">
    <header class="header">
      <el-row :gutter="30">
        <el-col :sm="24" :md="24" :lg="14" class="header__left">
          <h1 class="header__left__title">
            Học lập trình
            <span class="header__left__title--blue">Ngay từ ngày hôm nay</span>
          </h1>

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// Phone number
const re = /((09|03|07|08|05)+([0-9]{8})\b)/g

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var jsonData = JSON.parse(responseBody);
postman.setEnvironmentVariable("token", jsonData.data.token);

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const fetchData = async () => {
  const res = await fetch("https://restcountries.eu/rest/v2/alpha/col"); // fetch() returns a promise, so we need to wait for it

  const country = await res.json(); // res is now only an HTTP response, so we need to call res.json()

  console.log(country); // Columbia's data will be logged to the dev console
};

fetchData();

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.grid {
    width: 100%;
    display: block;
    padding: 0;
}

.grid.wide {
    max-width: 1200px;
    margin: 0 auto;
}

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import axios from 'axios'

const baseDomain = 'https://example.com'
const baseUrl = `${baseDomain}/api/v1`

export default axios.create({
  baseUrl,
  header: {  "Authorization": "Bearer yourToken" }
})

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function createElement(type, props, ...children) {
  return {
    type,
    props: {
      ...props,
      children: children.map(child =>
        typeof child === "object" ? child : createTextElement(child)
      )
    }
  };