Remove consecutive duplicate characters in a string javascript

Question

I have some string like 11122_11255_12_223_12 and the output I wish to have is this: 12_125_12_23_12
I already looked at this and also this a

Answer 1

If you are intersted in a non-regex way, you can split the items on the _, and then map that by creating a Set of characters which will remove duplicates. Then you just join the data back together. Like this:

var str = '11122_11255_12_223_12';
let result = str
  // Split on the underscore
  .split('_')
  // map the list
  .map(i =>
    // Create a new set on each group of characters after we split again
    [...new Set(i.split(''))].join('')
  )
  // Convert the array back to a string
  .join('_')

console.log(result)

Answer 2

I really like the regex solution. However, first thing which would come into my mind is a checking char by char with a loop:

const str = "11122_11255_12_223_12";
let last = "";
let result = "";
for(let i = 0; i < str.length; i++){
  let char = str.charAt(i);
  if(char !== last){
    result += char;
    last = char;
  }
}
console.log(result);

Answer 3

Easy and recursive way

let x = "11122_11255_12_223_12".split('');
let i = 0;
let j = 1;

function calc(x) {
  if (x[i] == x[j]) {
    x.splice(j, 1);
    calc(x);
  }
  
  if (j == x.length) {
    return x.join('');
  }
  
  i += 1;
  j += 1;
  calc(x);
}
console.log(calc(x));

Answer 4

You can use capture group and back-reference:

result = str.replace(/(.)\1+/g, '$1')

RegEx Demo

• (.): Match any character and capture in group #1
• \1+: Match 1+ characters same as in capture group #1