JavaScript remove adjacent duplicate letters [duplicate]

Question

I have seen a few examples of this, but they're either not in JS or are terribly inefficient (like the solution I have now). Basically what I want done is a function that takes in a string and removes any characters that are adjacent and the same. As an example, "jjjavvvaaassscript" would become "javascript". What I'm not looking for is where it would become "javscript" (eliminating the second "a"). I do have a working function shown below, but it's absolutely horrendous and I'm looking for a better way to do it.

function removeChar(text, index) {
    return(text.slice(0,index)+text.slice(index+1));
}

function removeDuplicates(text) {
    var prevChar = "";
    var finalT = text;
    var i = 0;
    for(i = 0; i < text.length; i++) {
        if(finalT.charAt(i) == prevChar) {
            if(i > finalT.length) {
                return finalT;
            } else {
                finalT = removeChar(finalT, i);
                i--;
            }
        } else {
            prevChar = finalT.charAt(i);
        }
    }
    return finalT;
}

Any help would be greatly appreciated!

CertainPerformance · Accepted Answer · 2021-04-08 02:29:05Z

1

I'd use a regular expression to match a character, then backreference it as many times as possible (so, for example, it'll match jjj, or a, or vvv, etc), and then replace with the one character:

const removeDuplicates = str => str.replace(/(.)\1*/g, '$1');
console.log(removeDuplicates('jjjavvvaaassscript'));

If you had to iterate more manually, similar to your current method, then:

const removeDuplicates = str => {
  let lastChar = str[0];
  let finalT = str[0];
  for (const char of str.slice(1)) {
    if (lastChar !== char) finalT += char;
    lastChar = char;
  }
  return finalT;
};
console.log(removeDuplicates('jjjavvvaaassscript'));

edited Apr 8, 2021 at 2:29

answered Apr 8, 2021 at 2:27

CertainPerformance

373k55 gold badges354 silver badges359 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Hao Wu Over a year ago

Maybe \1+ would be better, since you don't need to replace a character that has no duplicates

Collectives™ on Stack Overflow

JavaScript remove adjacent duplicate letters [duplicate]

1 Answer 1

1 Comment

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Linked

Related