JavaScript ES6

JavaScript was invented by Brendan Eich in 1995, and became an ECMA standard in 1997.

ECMAScript is the official name of the language.

ECMAScript versions have been abbreviated to ES1, ES2, ES3, ES5, and ES6.

Since 2016 new versions are named by year (ECMAScript 2016 / 2017 / 2018).

Arrow Function

const sum =(a,b)=> a+b
console.log(sum(2,6))
//prints 8

Default parameters

function print(a=5){
console.log(a)
}
print();
//prints 5

Let Scope

let a=3;
if(true){
let a=5;
console.log(a);//prints 5
}
console.log(a);//prints 3

Const

//can be assigned only once
var x = 50;
// Here x is 50
{
  const x = 16;
  console.log(x);// Here x is 16
}
console.log(x); // Here x is 50

Multiline String

console.log(`This is a 
multiline string`);

Template string

const name ='Chhetri'
const message =`Buddhadeb ${name}`
console.log(message)
//Prints Buddhadeb Chhetri

Exponent Operator

const byte =2 ** 8
console.log(byte)
//same as : Math.pow(2,8)

Spread Operator

const a=[1,2]
const b=[3,4]
const c=[...a,...b]
console.log(c) 
//[1,2,3,4]

String Includes()

console.log('apple'.includes('p'))
//Prints true
console.log('apple'.includes('tt'))
//prints false

String StartsWith()

console.log('ab'.repeat(3))
//prints 'ababab'

Destructuring array

let [a,b] =[3,7];
console.log(a);//3
console.log(b);//7

Destucturing object

let obj ={
a:55,
b:44
};
let{a,b}= obj;
console.log(a);
//55
console.log(b);
//44

Object property assignment

const a=2
const b=5
const obj={a,b}
//before es6:
//obj ={a:a,b:b}
console.log(obj)
//{a:2,b:5}

Object.Assign()

const obj1 ={a:1}
const obj2 ={b:2}
const obj3 =Object.assign({},obj1,obj2)
console.log(obj3)
//{a:1 ,b:2}

Promises with finally

promise
.then((result) => {...})
.catch((error) => {...})
.finally(() => { 
    //Logic independent of success/error 
})
/* The handeler is called when the promise is fulfilled or rejected.*/

Blog

Buddhadeb Chhetri