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 and etc
but there are not what I want as I described above.

actually, I used here for my purpose but something is wrong.

here is my code :

var str='11222_12_111_122_542_1212333_122';
var result = str.replace(/(1{2,}|2{2,}|3{2,}|4{2,}|5{2,}|6{2,}|7{2,}|8{2,}|9{2,})/g,'$1');
console.log(result);

and it is not working. it gives me the exact input in output.

as I mentioned above I have some string like 11122_11255_12_223_12 and the output I wish to have is this: 12_125_12_23_12, it means between the underlines is a number, and for each number if there are two or more digits next to each other(ex:223 has two 2), I want to keep just one of them.
thanks.

anubhava · Accepted Answer · 2019-04-11 15:57:07Z

29

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

answered Apr 11, 2019 at 15:57

anubhava

790k67 gold badges603 silver badges671 bronze badges

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

2 Comments

Andrés Montoya Over a year ago

What $1 means?

anubhava Over a year ago

That is beck reference for captured group no 1.

Danmoreng · Accepted Answer · 2019-04-11 16:13:29Z

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);

answered Apr 11, 2019 at 16:13

Danmoreng

2,3671 gold badge20 silver badges32 bronze badges

Comments

Ravi Shekhar · Accepted Answer · 2021-01-31 13:13:20Z

1

function removeAdjacentDuplicates(str) {
    let newStr = '';
    for (let i = 0; i < str.length; i++) {
        if (str[i] !== str[i + 1])
            if (str[i - 1] !== str[i])
                newStr += str[i];
    }
    return newStr;
}

answered Jan 31, 2021 at 13:13

Ravi Shekhar

213 bronze badges

1 Comment

René Höhle Over a year ago

perhaps you give some explanation to your solution to help other people to understand what you have made.

Get Off My Lawn · Accepted Answer · 2019-04-11 16:18:35Z

0

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)

answered Apr 11, 2019 at 16:18

Get Off My Lawn

36.6k47 gold badges201 silver badges380 bronze badges

Comments

adiga · Accepted Answer · 2019-08-19 20:13:05Z

0

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));

edited Aug 19, 2019 at 20:13

adiga

35.4k9 gold badges65 silver badges88 bronze badges

answered Aug 19, 2019 at 19:16

Nitesh Vuppala

474 bronze badges

1 Comment

adiga Over a year ago

How do I create a runnable stack snippet?

Collectives™ on Stack Overflow

Remove consecutive duplicate characters in a string javascript

5 Answers 5

2 Comments

Comments

1 Comment

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

2 Comments

Comments

1 Comment

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related