10 Fundamentals, JavaScript Developer’s should know

1. Try …Catch:

// code start to execute the whole code, unless it'll find any error
//if any error found in try , then catch is began to execute and execution doesnt blocked due to error. It gives the programmer the error message which helps the programmers to debug

2. Var Declarations and Hoisting:

3. Block-Level Declarations

4. Default Parameters Value in ES6

const add =(a=3, b=5) => {
return a + b;

add(4,2) // 6
add(4) // 9
add() // 8

5. Spread Operator

const pet = ['cat', 'dog', 'parrot'];

const wild = [...pet, 'wolf', 'lion'];
console.log(wild) // [ 'cat', 'dog', 'parrot', 'wolf', 'lion' ]
const pet = { animal-1: 'cat', animal-2: 'dog', animal-3: 'parrot'};
const wolf = {...pet, animal-4: 'wolf', animal-5: 'lion'};
// {
animal1: 'cat',
animal2: 'dog',
animal3: 'parrot',
animal4: 'wolf',
animal5: 'lion'

6. Block level function

7. Arrow Function:

function add(a,b){
return a+b

8. Cross Browser Testing


It is not necessary to tell “how code works” and “what it does”.

A Frontend Web Developer. Devoted to solving new problems and developing interactive web application