How to replace all occurrences of a string except the first one in JavaScript?

Question

I have this string:

hello world hello world hello world hello

and I need to get the following:

hello world hello hello hello

If I use:

str = str.replace('world', '');

it only removes the first occurrence of world in the above string.

How can I replace all the occurrences of it except the first one?

@Legman That is not an accurate duplicate. The OP isn't asking about all instances. — Charlie Fish, Apr 24 '18 at 23:41

Kristianmitk · Accepted Answer · 2018-07-16T21:27:56.940

20

You can pass a function to String#replace, where you can specify to omit replacing the first occurrence. Also make your first parameter of replace a regex to match all occurrences.

Demo

let str = 'hello world hello world hello world hello',
    i = 0;
    
str = str.replace(/world/g, m  => !i++ ? m : '');
console.log(str);

Note

You could avoid using the global counter variable i by using a IIFE:

let str = 'hello world hello world hello world hello';

str = str.replace(/world/g, (i => m => !i++ ? m : '')(0));
console.log(str);

edited Jul 16 '18 at 21:27

answered Apr 24 '18 at 23:44

Kristianmitk

4,528
5
26
46

You don't need to use regex for simple cases as in the question, you can match a string with `replaceAll`: `str.replaceAll('world', m => !i++ ? m : '');` – Rafael Tavares Jun 07 '21 at 14:19
just bear in mind that replaceAll is not nativelly supported in nodeJS version < 15. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replaceAll#browser_compatibility – Kristianmitk Sep 29 '21 at 07:25
That's true. For future readers: you can use `replaceAll` in some situations and add a polyfill if needed, as I stated in that answer: [Jest: TypeError: replaceAll is not a function](https://stackoverflow.com/a/67877325/8839059) – Rafael Tavares Sep 29 '21 at 12:10

Marcos Casagrande · Answer 2 · 2018-05-12T16:15:53.393

To provide an alternative to @Kristianmitk excellent answer, we can use a positive lookbehind, which is supported in Node.Js & Chrome >= 62

const string = 'hello world hello world hello world hello';

console.log(
  string.replace(/(?<=world[\s\S]+)world/g, '')
);
// or
console.log(
  string.replace(/(?<=(world)[\s\S]+)\1/g, '')
);

Using Symbol.replace well-known symbol.

The Symbol.replace well-known symbol specifies the method that replaces matched substrings of a string. This function is called by the String.prototype.replace() method.

const string = 'hello world hello world hello world hello';

class ReplaceButFirst {
     constructor(word, replace = '') {
         this.count = 0;
         this.replace = replace;
         this.pattern = new RegExp(word, 'g');
     }
     
     [Symbol.replace](str) {
          return str.replace(this.pattern, m => !this.count++ ? m : this.replace);
     }
}

console.log(
  string.replace(new ReplaceButFirst('world'))
);

This is also a very slick answer! Probs better for a Node script than a browser script. — TJBlackman, Apr 25 '18 at 00:37

Zohaib Ijaz · Answer 3 · 2018-04-24T23:51:29.497

1

In my solution, I am replacing first occurrence with a current timestamp, then replacing all occurrences and then finally replacing timestamp with world

You can also use str.split('world') and then join

var str = 'hello world hello world hello world hello';
var strs = str.split('world');
str = strs[0] + 'world' + strs.slice(1).join('');
console.log(str);

var str = 'hello world hello world hello world hello';

const d = Date.now()
str = str.replace('world', d).replace(/world/gi, '').replace(d, 'world');

console.log(str);

edited Apr 24 '18 at 23:51

answered Apr 24 '18 at 23:38

Zohaib Ijaz

21,926
7
38
60

2

what happens if the timestamp itself a word in that sentence? – Rama Adaikkalam Apr 24 '18 at 23:49

score 1 · Answer 4 · answered Apr 24 '18 at 23:45

1

var str = 'hello world hello world hello world hello'; 

var count = 0;
var result = str.replace(/world/gi, function (x) {
  if(count == 0) {
      count++;
      return x;
    } else {
      return ''; 
    }
});

console.log(result);

answered Apr 24 '18 at 23:45

Rama Adaikkalam

665
1
7
14

score 0 · Answer 5 · answered Apr 24 '18 at 23:43

I would do it like this:

Get the substring up until and including the first occurrence.
Append to that the substring after the first occurrence, with all other occurrences removed:

    function replaceExceptFirst(str, search) {
         let index = str.indexOf(search);
         return str.substring(0, index + search.length) + 
             str.substring(index + search.length).replace(/world/g, '')
    }
    
    console.log(replaceExceptFirst('hello world hello world world hello', 'world'))

How to replace all occurrences of a string except the first one in JavaScript?

5 Answers5