Remove whitespaces inside a string in javascript

You can use

"Hello World ".replace(/\s+/g, '');

trim() only removes trailing spaces on the string (first and last on the chain). In this case this regExp is faster because you can remove one or more spaces at the same time.

If you change the replacement empty string to '$', the difference becomes much clearer:

var string= '  Q  W E   R TY ';
console.log(string.replace(/\s/g, '$'));  // $$Q$$W$E$$$R$TY$
console.log(string.replace(/\s+/g, '#')); // #Q#W#E#R#TY#

Performance comparison - /\s+/g is faster. See here: http://jsperf.com/s-vs-s

Update

You can use too:

console.log(string.replaceAll(/\s/, '#')); // #Q#W#E#R#TY#

String.prototype.replaceAll()

The best way is to do it this way if you only want to replace the whitespaces:

let str = " H e l l o 1  5 9   ";
let onlyCharacters = str.replaceAll(" ", "");

// onlyCharacters = Hello159

I used str.replace(/\s/g, ""); a lot but it does not work in all the browsers for example it does not work in duckduckgo in android and also it does not work in android webview.

Probably because you forgot to implement the solution in the accepted answer. That's the code that makes trim() work.

update

This answer only applies to older browsers. Newer browsers apparently support trim() natively.

You can use Strings replace method with a regular expression.

"Hello World ".replace(/ /g, "");

The replace() method returns a new string with some or all matches of a pattern replaced by a replacement. The pattern can be a string or a RegExp

RegExp

• / / - Regular expression matching spaces

• g - Global flag; find all matches rather than stopping after the first match

const str = "H    e            l l       o  World! ".replace(/ /g, "");
document.getElementById("greeting").innerText = str;

<p id="greeting"><p>

You could use a recursive solution:

function removeWhitespaces(string, i = 0, res = "") {
  if (i >= string.length)
    return res
  else
  if (string[i] == " ")
    return removeWhitespaces(string, i + 1, res)
  else
    return removeWhitespaces(string, i + 1, res += string[i])
}

console.log(removeWhitespaces(" Hello World,   how is it going ? "))

Precise answer to how to approach this depends on precise intention. To remove any and/or all white space characters you should use:

's t r i n g'.replace(\s+\g, '')

If the intention is to only remove specific types of whitespaces (ie. thin or hair spaces) they have to be listed explicitely like this:

's t r i n g'.replace(\ |\t \g, '')

However if the intention is to remove just plain spaces only, then performance wise the best solution is:

's t r i n g'.replace(' ', '')

Here is a benchmark comparing results. There is a slight performance variance amongst the regexp solutions, but its rather insignificant. However string based replace outperforms regexps in the linked benchamrk by about an order of magnitude of ops/s. (https://jsbench.me/drlfuphfhk/1)