The Best JavaScript Tips & Tricks (ES6 / ECMAScript 6)

I’ve been maintaining several
JavaScript driven websites. I found it is not easy to quickly make an update or enhancement in JavaScript when I only do it once in a while. So I decided to create this page to document all the tips and tricks that help me to keep my websites both personal and commercial to run at the optimal state.
I will cover JavaScript up to ECMAScript 6, also known as ECMAScript 2015. This is the latest version of the ECMAScript standard as of September 2019. ES6 is a significant update to the language, and the first update to the language since ES5 was standardized in 2009.

  1. use === instead of ==
  2. The == (or !=) operator performs an automatic type conversion if needed. The === (or !==) operator will not perform any conversion. It compares the value and the type, which could be considered faster than ==.


    [10] === 10    // is false
    [10]  == 10    // is true
    '10' == 10     // is true
    '10' === 10    // is false
     []   == 0     // is true
     [] ===  0     // is false
     '' == false   // is true but true == "a" is false
     '' ===   false // is false


  3. Create an object constructor
  4. function Person(firstName, lastName){
        this.firstName =  firstName;
        this.lastName = lastName;        
    var Saad = new Person("Saad", "Mousliki");


  5. Create Anonymous Function or Self-calling Function
  6. This is usually called a Self-Invoked Anonymous Function or Immediately Invoked Function Expression (IIFE). It is a function that executes automatically when you create it, and has the following syntax:

        // some private code that will be executed automatically
        var result = a+b;
        return result;
  7. Use Await To Make Several Asynchronous Calls
  8. By using Promise.all and await keyword, it’s possible to await multiple async functions to finish :

    await Promise.all([anAsyncCall(), thisIsAlsoAsync(), oneMore()])

JavaScript References:

Mozilla array