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Master the JavaScript Interview

Remove Dupes

Explore how to create JavaScript functions that remove duplicate characters from strings while maintaining their original order. Understand two approaches: using objects and arrays for tracking uniqueness and using the ES2015 Set data structure to simplify code. Learn about the time and space complexities involved to write efficient solutions.

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Remove Dupes

Instructions

Write a function that takes in a string and returns a new string. The new string should be the same as the original with every duplicate character removed.

Input: String

Output: String

Examples

'abcd' -> 'abcd'
'aabbccdd' -> 'abcd'
'abcddbca' -> 'abcd'
'abababcdcdcd' -> 'abcd'
Node.js
function removeDupes(str) {
    // Your code here
}

Solution 1

Node.js
function removeDupes(str) {
    const characters = {};
    const uniqueCharacters = [];
    
    for(let i = 0; i < str.length; i++) {
        const thisChar = str[i];
        if(!characters[thisChar]) {
            characters[thisChar] = true;
            uniqueCharacters.push(thisChar);
        }
    }
    
    return uniqueCharacters.join('');
}

How it Works

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