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ReactJs : Tutorial-02 – ES6
ES6 – ECMAScript 6
Standardized JavaScript
Version 6 in 2015 (ECMAScript 2015)
ReactJs uses ES6
New Features:
o Classes
o Arrow Functions
o Variables (let, const, var)
ES6 – Class:
A class is a type of function.
Property in constructor.
Example:
class Car {
constructor(name) {
this.brand = name;
}
}
mycar = new Car("BMW");
Method in Classes
class Car {
constructor(name) {
this.brand = name;
}
present() {
return 'I have a ' + this.brand;
}
}
mycar = new Car("Ford");
mycar.present();
Output
I have a Ford
ReactJs : Tutorial-02 – ES6
Class Inheritance
To create a class inheritance, use the extends keyword.
A class created with a class inheritance inherits all the methods from another class:
Example
Create a class named "Model" which will inherit the methods from the "Car" class:
class Car {
constructor(name) {
this.brand = name;
}
present() {
return 'I have a ' + this.brand;
}
}
class Model extends Car {
constructor(name, mod) {
super(name);
this.model = mod;
}
show() {
return this.present() + ', it is a ' + this.model
}
}
mycar = new Model("Ford", "Mustang");
mycar.show();
ReactJs : Tutorial-02 – ES6
Arrow Functions
Arrow functions were introduced in ES6.
Arrow functions allow us to write shorter function syntax:
Before:
hello = function() {
return "Hello World!";
}
With Arrow Function:
hello = () => {
return "Hello World!";
}
Arrow Functions Return Value by Default:
hello = () => "Hello World!";
Arrow Function With Parameters:
hello = (val) => "Hello " + val;
Arrow Function Without Parentheses:
hello = val => "Hello " + val;
ReactJs : Tutorial-02 – ES6
Variables
Before ES6 there were only one way of defining your variables: with the var keyword.
Now, with ES6, there are three ways of defining your variables: var, let, and const.
 var has a function scope, not a block scope.
 let has a block scope.
 const has a block scope. const is a variable that once it has been created, its value can never
change.

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  • 1. ReactJs : Tutorial-02 – ES6 ES6 – ECMAScript 6 Standardized JavaScript Version 6 in 2015 (ECMAScript 2015) ReactJs uses ES6 New Features: o Classes o Arrow Functions o Variables (let, const, var) ES6 – Class: A class is a type of function. Property in constructor. Example: class Car { constructor(name) { this.brand = name; } } mycar = new Car("BMW"); Method in Classes class Car { constructor(name) { this.brand = name; } present() { return 'I have a ' + this.brand; } } mycar = new Car("Ford"); mycar.present(); Output I have a Ford
  • 2. ReactJs : Tutorial-02 – ES6 Class Inheritance To create a class inheritance, use the extends keyword. A class created with a class inheritance inherits all the methods from another class: Example Create a class named "Model" which will inherit the methods from the "Car" class: class Car { constructor(name) { this.brand = name; } present() { return 'I have a ' + this.brand; } } class Model extends Car { constructor(name, mod) { super(name); this.model = mod; } show() { return this.present() + ', it is a ' + this.model } } mycar = new Model("Ford", "Mustang"); mycar.show();
  • 3. ReactJs : Tutorial-02 – ES6 Arrow Functions Arrow functions were introduced in ES6. Arrow functions allow us to write shorter function syntax: Before: hello = function() { return "Hello World!"; } With Arrow Function: hello = () => { return "Hello World!"; } Arrow Functions Return Value by Default: hello = () => "Hello World!"; Arrow Function With Parameters: hello = (val) => "Hello " + val; Arrow Function Without Parentheses: hello = val => "Hello " + val;
  • 4. ReactJs : Tutorial-02 – ES6 Variables Before ES6 there were only one way of defining your variables: with the var keyword. Now, with ES6, there are three ways of defining your variables: var, let, and const.  var has a function scope, not a block scope.  let has a block scope.  const has a block scope. const is a variable that once it has been created, its value can never change.