# JavaScript | Move Zeroes

## Interview Question

This question comes under a broad category of “Array Transformation”.

Given an integer array `nums`, move all `0`'s to the end of it while maintaining the relative order of the non-zero elements.

Note that you must do this in-place without making a copy of the array.

Example:

`Input: nums = [0,1,0,3,12]Output: [1,3,12,0,0]`

Solution:

The 2 requirements of the question are:

1. Move all the 0’s to the end of array.
2. All the non-zero elements must retain their original order.

Let's look into two implementation -

In the first implementation,

• the first loop deletes the zeros using splice().
• the second loop pushes the zeros to the end of arrays using push().
`var moveZeroes = function(nums) {    let zeros = 0  for (let i = 0; i < nums.length; i++) {   let isZero = nums[i] === 0     if (isZero){        zeros++        nums.splice(i, 1)        i--      }    }  for (let i = 0; i < zeros; i++){      nums.push(0)  } return nums};`

Second Implementation,

• using one for loop, we will delete the zeros using splice() and push the zeros to the end of the array using push().
`var moveZeroes = function(nums) {   for (let i = nums.length - 1; i >= 0; i--) {     nums[i] === 0 && nums.splice(i, 1) && nums.push(0);   } return nums};`

Summary

• use splice() method of the array, to delete the zeros and add those zeros to the end of the array using push().

This problem is very popular in coding interviews.

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