szaranger

const element = document.getElementById('button');

function onClick(event) {
    element.innerHtml = 'text';
}

element.addEventListener('click', onClick);
// Do stuff
// ...
// Remove handlers

szaranger

const data = getData();

setInterval(function() {
    const node = document.getElementById('id');
    
    if(node) {
        // Do stuff with node and data.
        node.innerHTML = JSON.stringify(data));
    }
}, 1000);

szaranger

let original = null;

const duplicate = function () {
  const isOriginal = original;
  
  const unused = function () {
    if (isOriginal) { 
      console.log("I'm unused"); 
    }
  };

szaranger

function outer() {
    const obj = {
        id: 1,
        name: "David",
    };
    function closure() {
        const { name } = obj;
        sayHello(name);
    }
}

szaranger

// This will also become a global variable as arrow functions
// do not have a contextual `this` and instead use a lexical `this`
const hey = () => {
    this.foo = "Hello world!";
}

szaranger

// This will also become a global variable as global functions have
// global `this` as the contextual `this` in non-strict mode
function hey() {
  this.foo = "Hello world!";
}

szaranger

// This will be hoisted as a global variable
function hey() {
  foo = "Hello world!";
}

szaranger

fucntion Person(name, dob) {
  this.name = name;
  this.dob = dob;
}

const sherlock = new Person({
  name: 'Sherlock Holmes',
  dob: '01-06-1852';
});

szaranger

fucntion Person(name, dob) {
  this.name = name;
  this.dob = dob;
}

const john = new Person({
  name: 'Dr John Dollar',
  dob: '01-08-1866'
});

szaranger

import useSWR from 'swr';

const Post = () => {
  const { data, error } = useSWR('/api/post/123', fetch);
  
  if (error) {
     return <div>Error loading post!</div>;
   }
   
  if (!data) {