We have an array of literals that contains some duplicate values appearing for many times like this −
const arr = [1, 4, 3, 3, 1, 3, 2, 4, 2, 1, 4, 4];
We are required to write a JavaScript function that takes in this array and pick out all the duplicate entries from the original array and only once.
Therefore, for the above array, the output should be −
const output = [1, 4, 3, 2];
Example
The code for this will be −
const arr = [1, 4, 3, 3, 1, 3, 2, 4, 2, 1, 4, 4]; const removeDuplicate = arr => { const res = []; for(let i = 0; i < arr.length; i++){ if(arr.indexOf(arr[i]) !== arr.lastIndexOf(arr[i])){ if(!res.includes(arr[i])){ res.push(arr[i]); }; }; }; return res; }; console.log(removeDuplicate(arr));
Output
The output in the console −
[1, 4, 3, 2]