Filtering out the non-unique value to appear only once in JavaScript

JavascriptWeb DevelopmentFront End TechnologyObject Oriented Programming

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]
raja
Published on 15-Oct-2020 12:47:14
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