How to Find Unique Characters in a JavaScript String

We often need to find unique characters to work on different elements of any string. For example, we have a string (‘hello world’) and now we want to find the unique or unique characters in this string. In today's blog, we will discuss some methods on how to easily solve this problem using JavaScript.

 

Using for loop and includes method

function getUniqueCharacters(str) {
  let uniqueChars = ''; // Empty string to store unique characters

  for (let char of str) {
    // If the character is not already in the unique string, add it
    if (!uniqueChars.includes(char)) {
      uniqueChars += char;
    }
  }

  return uniqueChars;
}

// Example usage
const input = "hello world";
console.log(getUniqueCharacters(input)); // "helo wrd"

Using filter method

function getUniqueCharacters(str) {
  return str
    .split('') // Splitting the string into an array of characters
    .filter((char, index, arr) => arr.indexOf(char) === index) // Filtering only the unique characters
    .join(''); // Converting the array back into a string
}

// Example usage
const input = "hello world";
console.log(getUniqueCharacters(input)); // "helo wrd"

Using reduce method

function getUniqueCharacters(str) {
  return str.split('').reduce((uniqueChars, char) => {
    // If the character is not already in the unique string, add it
    return uniqueChars.includes(char) ? uniqueChars : uniqueChars + char;
  }, '');
}

// Example usage
const input = "hello world";
console.log(getUniqueCharacters(input)); // "helo wrd"

Using regular expression (RegEx)

function getUniqueCharacters(str) {
  return str.replace(/(.)(?=.*\1)/g, ''); // Retains the first occurrence of each character and removes the rest
}

// Example usage
const input = "hello world";
console.log(getUniqueCharacters(input)); // "helo wrd"

 

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