JavaScript ES6

#javascript #beginners #webdev #productivity

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.*/

Top comments (10)

Chris Gustin • Jan 23 '22

For the Template String example, the line with the template string needs to be wrapped in back ticks instead of single/double quotes or it won’t parse.

James Thomson • Jan 23 '22 • Edited

The Object.Assign example has a similar issue. object needs to be Object or else it'll throw a reference error. Same with the promise example. 🤦‍♂️ ...In fact, there are a lot of examples here missing closing quotes or with improper casing which will throw errors.