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?

Answer 1

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);

Answer 2

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')) );

Answer 3

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);

Answer 4

 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);

Answer 5

I would do it like this:

1. Get the substring up until and including the first occurrence.
2. 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'))