How to find unique characters of a string in JavaScript ?

Last Updated : 24 Sep, 2021

The purpose of this article is to find unique characters in a string using JavaScript.

Example:

Hey geek! The constant emerging technologies in the world of web development always keeps the excitement for this subject through the roof. But before you tackle the big projects, we suggest you start by learning the basics. Kickstart your web development journey by learning JS concepts with our JavaScript Course. Now at it's lowest price ever!

Input:  Geeksforgeeks
Output: Geksforg

Input:  Geeksforgeeks is a great site for computer science
Output: Geksforg Iaticmpun

To achieve this, we have the following approaches:

Approach 1: This is a naive approach to find the unique characters from a string. In this approach, we create a variable name uniq and we are iterating over the string using the for loop and at every iteration, we are checking if the uniq contains the character.

Javascript

<script>
function findUnique(str){
  // The variable that contains the unique values
  let uniq = "";
   
  for(let i = 0; i < str.length; i++){
    // Checking if the uniq contains the character
    if(uniq.includes(str[i]) === false){
      // If the character not present in uniq
      // Concatenate the character with uniq
      uniq += str[i]
    }
  }
  return uniq;
}
 
console.log(findUnique("Geeksforgeeks"))
console.log(findUnique("Geeksforgeeks Is a great site for computer science"))
</script>

Output:

"Geksforg"

"Geksforg Iaticmpun"

Approach 2: In this method, we use the set data structure. The set data structure contains only unique values, and we take the advantage of it. So to extract the unique values from string using Set we follow the steps below.

Using the split() method convert the string into an array.
Create a Set using new Set() and pass the converted array into it.
Now convert the set into an array using spread operator e.g: […set]
And then join that array to make a string.

Javascript

<script>
// Javascript program to extract unique characters from a string
function findUnique(str){
 
  // Split the string to make array
  str = str.split("")
   
  // Create a set using array
  str = new Set(str);
   
  // Convert the set into array using spread 
  // operator and join it to make string
  str = [...str].join("");
   
  return str;
}
 
 
console.log(findUnique("Geeksforgeeks"))
console.log(findUnique("Geeksforgeeks Is a great site for computer science"))
</script>

Output:

"Geksforg"

"Geksforg Iaticmpun"

Approach 3: In this approach first, we convert the string into an array using the spread operator e.g. […str] and then we apply the reduce method on that array.

Javascript

<script>
// Javascript program to extract unique characters from a string
function findUnique(str){
  return [...str].reduce((acc, curr)=>{
    return acc.includes(curr) ?  acc  :  acc + curr;
  }, "")
}
 
 
console.log(findUnique("Geeksforgeeks"))
console.log(findUnique("Geeksforgeeks Is a great site for computer science"))
</script>

Output:

"Geksforg"
"Geksforg Iaticmpun"

My Personal Notes

Related Articles

Table of Contents

How to find unique characters of a string in JavaScript ?

Javascript

Javascript

Javascript