In Javascript you can add one or more element into an array with the hepl of push() method and it will return new length of an array .
Syntax ->
arrayname.push(element1, element2 ,.........elementN )
Parameters ->
elementN- > New Element/s will be added to the end of the array .
Return->It will return new lenght of an array after adding the element into an array .

Example ->
1) Adding New elements into an array ->

var names = [ 'Mukesh ' , ' Ravi ' , 'Abhishek ' ,  ' Ayush ' ] ; <br>
var arrnames = names.push( 'Ishan ' , ' Medha ') ; <br>
document.write( names ) ; //output -> Mukesh   Ravi  Abhishek   Ayush   Ishan   Medha <br>
 document.write( arrnames ) ; //output -> It will return the length of new array "6".

2) Merging of two arrays

var fname = [ 'Mukesh ' , ' Ravi ' , 'Abhishek ' ,  ' Ayush ' ] ; <br>
var lname = [ ' Tomar ' , ' Badoni ' , ' Kumar ' ,  ' Gupta ' ] ; <br>
Array.prototype.push.apply(fname , lname) ;<br>
console.log(fname) // output ->  'Mukesh ' , ' Ravi ' , 'Abhishek ' ,  ' Ayush '  ' Tomar ' , ' Badoni ' , ' Kumar ' ,  ' Gupta '