# Using recursion to remove consecutive duplicate entries from an array - JavaScript

JavascriptWeb DevelopmentFront End TechnologyObject Oriented Programming

We are supposed to write a function that takes in an array of number/string literals. The function should remove all the redundant consecutive elements of the array without using extra memory space.

For example, if the input array is −

const arr = [17, 17, 17, 12, 12, 354, 354, 1, 1, 1];

Then the output should be −

const output = [17, 12, 354, 1];

## Example

Following is the code −

const arr = [17, 17, 17, 12, 12, 354, 354, 1, 1, 1];
const comp = (arr, len = 0, deletable = false) => {
if(len < arr.length){
if(deletable){
arr.splice(len, 1);
len--;
}
return comp(arr, len+1, arr[len] === arr[len+1])
};
return;
};
comp(arr);
console.log(arr);

## Output

This will produce the following output in console −

[ 17, 12, 354, 1 ]
Published on 18-Sep-2020 12:49:18