ES6 Features in JavaScript

 ES6

1.  ES6 is a new standardized interpretation of JavaScript that was released in 2015. 

2.  It's also referred to as ECMAScript 2015.

3. ES6 is the base for ultramodern programming languages like Angular and ReactJs. With Object- Acquainted Classes, Arrow Functions, String Literals, and far more.

4.  ES6 is a point-rich advancement to ES5, the former interpretation of JavaScript.

 

The following is a list of top ES6 features that every JavaScript developer should be aware of.

1. Default parameters

2. Destructuring assignment

3. let and const

 

 

1. Default parameter

 

This can be achieved with default function parameters in JavaScript since the default value for function parameters is undefined.

 

 

Example:

 

Before ES6

 

Function addNumber (num1,num2){

Return num1+num2;

};

addNumber(10,5) //return 15

addNumber(5) //return NaN as num2 is undefined

 

 

 

 

       With ES6

 

Function addNumber (num1, num2 =10){

Return num1+num2;

};

addNumber(10,5) //return 15

addNumber(5) //return 15 as num2  has default value=10

 

Default function parameters allow being initialized with default values if no value or undefined is passed.

 

 

2. Destructuring assignment

1.     The 2 most used data structures in JavaScript are Object and Array.

2.     Destructuring assignment is a special syntax that allows us to “unpack values” from arrays/properties from objects into a bunch of variables.

3.     Simplification of restructuring is to break down a complex structure into simpler parts. 

4.     Destructuring Assignment defined on the left-hand side.

 

 

1. Array destructuring

                  Example: 1.

 

        Let X, Y:

        [X, Y] = [10,20]

            console.log(x); //10

             console.log(y) //20

 

2. Object destructuring

 

                Example: 2.

             ({X, Y} = {X=10, Y=20});

              console.log(x); //10

               console.log(y) //20

 

 

3. Let and const

1. Let

1. Let and const are block scoped.

2. Variable declared as let are in the block scope

Example:

 

   For(let i=0; i<3; i++){

  Console.log(i);

  }

   Console.log(i)

  Output

  1

  2

  3

 

3. Hosting is not allowed

Example:

 

X=8

Console.log(x);

Let x;

 

Output

error

Cannot access 'X before initialization

 

4. Let is allowing to reassign values.

Example:

 

Let V1 =1;

V1 = 30;

Console.log(v1);

 

Output

30

 

 

5. Let are not allowed to redeclaration of the variable

  Example:

 

Let V1 =1;

Let V1 = 30;

Console.log(v1);

 

Output

error

Uncaught SyntaxError: Identifier 'v1' has already been declared

 

2. Const

1. Variable declared as const are in the block scope

Example

 

     {

     const x = 2;

     console.log(x);

      }  console.log(x);

Output

2

Error

Uncaught ReferenceError: x is not defined

 

2. Hosting is not allowed

 Example:

 

X=8

Console.log(x);

const x;

 

Output

error

Cannot access 'X before initialization

 

3. Const is not allowing to reassign value.

Example:

 

     const v1 = 1;

      v1 = 30;

      console.log(v1);

 

Output

error

Uncaught Type Error: Assignment to constant variable.

 

4. Const is not allowed to redeclaration of the variable

 

const v1 = 1;

 

const v1 = 30;

 

console.log(v1)

 

Output

error

Uncaught SyntaxError: Identifier 'v1' has already been declared