JavaScript: Remove duplicate items from an array, ignore case sensitivity

JavaScript Array: Exercise-14 with Solution

Remove Duplicates

Write a JavaScript program to remove duplicate items from an array (ignore case sensitivity).

Visual Presentation:

Sample Solution-1:

JavaScript Code:

// Function to remove duplicate elements from an array
function removeDuplicates(num) {
  // Initialize variables: x for iteration, len for array length, out for the result array, obj for object to track unique elements
  var x,
      len = num.length,
      out = [],
      obj = {};

  // Iterate through the input array and add each element to the object with a value of 0
  for (x = 0; x < len; x++) {
    obj[num[x]] = 0;
  }

  // Iterate through the object and push each unique element to the result array
  for (x in obj) {
    out.push(x);
  }

  // Return the array containing unique elements
  return out;
}

// Initialize an array with duplicate elements
var Mynum = [1, 2, 2, 4, 5, 4, 7, 8, 7, 3, 6];

// Call the removeDuplicates function with the array and store the result
var result = removeDuplicates(Mynum);

// Output the original array and the result array without duplicates
console.log(Mynum);
console.log(result);

Sample Output:

[1,2,2,4,5,4,7,8,7,3,6]
["1","2","3","4","5","6","7","8"]

Flowchart:

Sample Solution-2:

Removing duplicates from an array in JavaScript can be done in a variety of ways, such as using Array.prototype.reduce(), Array.prototype.filter() or even a simple for loop. But there's an easier alternative. JavaScript's built-in Set object is described as a collection of values, where each value may occur only once. A Set object is also iterable, making it easily convertible to an array using the spread (...) operator.

JavaScript Code:

// Source: https://bit.ly/3hEZdCl
// Remove duplicates from a JavaScript array using the Set data structure
// Define an array 'nums' with duplicate elements
const nums = [1, 2, 2, 3, 1, 2, 4, 5, 4, 2, 6];

// Create a new Set from the array to automatically remove duplicates
const uniqueNumsSet = new Set(nums);

// Convert the Set back to an array using the spread operator
const uniqueNumsArray = [...uniqueNumsSet];

// Output the array with duplicates removed
console.log(uniqueNumsArray);

Output:

[1,2,3,4,5,6]

Live Demo:

See the Pen JavaScript - Remove duplicate items from an array, ignore case sensitivity - array-ex- 14 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that removes duplicate items from an array using a Set and returns the unique elements.
• Write a JavaScript function that iterates through an array and constructs a new array containing only unique values.
• Write a JavaScript function that filters duplicates from an array with mixed data types based on strict equality.
• Write a JavaScript function that uses a hash map to record frequencies and then removes duplicates accordingly.

Go to:

• JavaScript array Exercises Home ↩
• JavaScript Exercises Home ↩

PREV : Add Items to Array.
NEXT : Display Colors with Ordinals.

Contribute your code and comments through Disqus.