ES6 Arrow Functions

ES6 Arrow Functions

 

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Arrow function in es6 anonymous function. It does not have any name and does not start with function keyword.

Arrow function in ES6:

 

var arrowfun = () => {  
    console.log("Example Arrow Function");     
   };  

Optional parentheses for the single parameter

var data  = n => {  
    console.log(n);  
}  
data(10);  

Optional braces for single statement/parameter and the empty braces if there is no parameter to be passed.

var display = () => console.log( "Hello World" );  
display();  

Arrow function with multiple parameters:

let sum = (a, b) => a + b;
document.write(sum(10, 20)); // Output 30

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Arrow function with default parameters:

In ES6, parameters can initialize with some default values, if there is no value passed to it, or it is undefined. You can see the illustration for the same in the following code:

For example

var display = (a, b=200) => {
    console.log(a + " " + b);
}
 

display(100);

o/p 

 100 200

display(100,300);

100 300 // default value overwritten

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Arrow function with Rest parameters:

 

Rest parameters allow us to pass any number of parameters of the same type.

Declaring the rest parameter:

the parameter prefixed with the spread operator with three dots(...)

example :

var display = (a, ...args) => {  
    console.log(a + " " + args);  
} 

 display (10,20,30,40,50,60,70,80); 

o/p

10 20 30 40 50 60 70 80