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

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]

AmitDiwan

Published on 15-Oct-2020 09:17:14

• Related Questions & Answers
• Filtering out only null values in JavaScript
• Program to pick out duplicate only once - JavaScript
• Filtering string to contain unique characters in JavaScript
• Get count of values that only appear once in a MySQL column?
• Filtering out numerals from string in JavaScript
• Filtering out primes from an array - JavaScript
• Array elements that appear more than once?
• Array elements that appear more than once in C?
• Select a value from MySQL database only if it exists only once from a column with duplicate and non-duplicate values
• Detecting the first non-unique element in array in JavaScript
• Matching Only Once in Perl
• Add two array keeping duplicates only once - JavaScript
• Finding the only unique string in an array using JavaScript
• Show the background image only once with CSS
• Number of non-unique characters in a string in JavaScript