Let's Learn ES6 - Arrow Functions

01-Arrow-Functions-add.js

// 1 
let add = (a,b) => {
  return a+b;
}
console.log(add(4,5));

// 2

let add = (a,b) => a+b;
console.log(add(4,5));

02-Arrow-Functions-Map.js

//////////////////////////////
//1 
let numbers = [1,2,3,4,5];
let doubled = numbers.map(function(n){
  return n*2;
});
console.log(doubled);
/* output
[2, 4, 6, 8, 10]
*/


//////////////////////////////
// 2
let numbers = [1,2,3,4,5];
let doubled = numbers.map(n => n*2);
console.log(doubled);

03-Arrow-Functions-Object.js

//1
let person ={
  name: 'Kishan',
  sayName: function() {
    console.log(`I am ${this.name}`);
  }
}
person.sayName();
/*
output
"I am Kishan"
*/

/////////////////////////////////////////
//2
let person ={
  name: 'Kishan',
  sayName: () => {
    console.log(`I am ${this.name}`);
  }
}
person.sayName();
/*
TypeError: Cannot read property 'name' of undefined
    at Object.sayName 
    
Cz Arrow function have Lexical scope
Lexical Scope : scope of a variable so that it may only be called (referenced)
from within the block of code in which it is defined.
*/


////////////////////////////////////
//3
let person ={
  name: 'Kishan',
  sayName() {
    console.log(`I am ${this.name}`);
  }
}
person.sayName();
/*
output
"I am Kishan"
*/

04-Arrow-Functions-Array.js

//1
let person = {
  name: 'Kishan',
  hobbies: ['One','Two','Three'],
  showHobbies: function(){
    
    this.hobbies.forEach(function(hobby){
      console.log(`${this.name} is ${hobby}`);
    });
    
  }
}
person.showHobbies();
/*
output:
"JS Bin Output  is One"
"JS Bin Output  is Two"
"JS Bin Output  is Three"
*/

/////////////////////////////
//2
let person ={
  name: 'Kishan',
  hobbies: ['One','Two','Three'],
  showHobbies: function(){    
    this.hobbies.forEach(hobby => {
      console.log(`${this.name} is ${hobby}`);
    });    
  }
}
person.showHobbies();
/* Output:
"Kishan is One"
"Kishan is Two"
"Kishan is Three"
*/

//////////////////
//3
let person ={
  name: 'Kishan',
  hobbies: ['One','Two','Three'],
  showHobbies: function(){
    let self = this;
    this.hobbies.forEach(function(hobby){
      console.log(`${self.name} is ${hobby}`);
    });
    
  }
}
person.showHobbies();
/* Output:
"Kishan is One"
"Kishan is Two"
"Kishan is Three"
*/