Javascript .splice() and .push() error

Question

I have an array array1 and i store its copy in another variable say array2. Now when i try to push a value to array1, the value gets pushed in array2 aswell even though array2 is assigned before pushing value to array1. this happens in .splice() method too.

var array1 = [1,2,3];
var array2 = array1;
array1.push(4);
alert(array1);
alert(array2);

fiddle

Answer 1

You have to clone your first array like this :

var array2 = array1.slice(0);

Updated fiddle

Answer 2

JavaScript has primitive types and reference types.Array is a reference type. Array2 get the reference, so the modification of the array1 will affect the array2 .you can also use this code:

var array1 = [1,2,3];
var array2 = array1.concat();
array2.push(4);
alert(array1);
alert(array2);