Regex, Remove Whitespace and All Other Characters

Javascript Regular Expression Remove Spaces

I would recommend you use the literal notation, and the \s character class:

//..
return str.replace(/\s/g, '');
//..

There's a difference between using the character class \s and just ' ', this will match a lot more white-space characters, for example '\t\r\n' etc.., looking for ' ' will replace only the ASCII 32 blank space.

The RegExp constructor is useful when you want to build a dynamic pattern, in this case you don't need it.

Moreover, as you said, "[\s]+" didn't work with the RegExp constructor, that's because you are passing a string, and you should "double escape" the back-slashes, otherwise they will be interpreted as character escapes inside the string (e.g.: "\s" === "s" (unknown escape)).

Regular expression for removing whitespaces

This can be done in a single String#replace call:

var repl = str.replace(/^\s+|\s+$|\s+(?=\s)/g, "");

// gives: "tushar is a good boy"

How do I remove all whitespaces except those between words with Regular Expression in Javascript

Method 1

See regex in use here

\B\s+|\s+\B

\B Matches a location where \b doesn't match
\s+ Matches one or more whitespace characters

const r = /\B\s+|\s+\B/gconst s = ` hello world! , this is Cecy `
console.log(s.replace(r, ''))

Replace all whitespace characters

You want \s

Matches a single white space
character, including space, tab, form
feed, line feed.

Equivalent to

[ \f\n\r\t\v\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]

in Firefox and [ \f\n\r\t\v] in IE.

str = str.replace(/\s/g, "X");

Javascript Regex: How to remove all whitespaces around certain character?

This will do the trick:

var text = 'text ( 4 |-4 | 1 "test"  )  [ 0 50 90 ]';text = text.replace(/\s*([|()[\]])\s*/g, '$1');
alert(text)

JavaScript Regex - Remove Whitespace from Start and End

\s means whitespace characters in regex, like <space>, <tab>, etc.
^ means the beginning of the string
$ means the end of the string
| means OR (match the left side or the right side)
+ means 1 or more (based off of the rule on the left)
/a regex/g the g means "global", aka "match multiple times" since you could need to match at the beginning AND end

So the regex means:

/^\s+|\s+$/g
/         /       Wrap the regex (how you do it in JS)
 ^\s+             Try to match at the beginning one or more whitespace chars
     |            Or...
      \s+$        Try to match whitespace chars at the end
           g      Match as many times as you can

String.prototype.replace replaces the match(es) found in the regex with the string provided as the 2nd argument, in this case an empty string.

So the process internally is:

Look for all sections that match the regex (which will be the whitespace at the beginning and the whitespace at the end
Replace each match with "", removing those matches entirely

let hello = "   Hello, World!  ";
let wsRegex = /^\s+|\s+$/g; 
let result = hello.replace(wsRegex, "");

console.log('"' + result + '"');

Remove white-space after / in a string with RegEx

You may match a forward slash (\/, escaped since / is used as a regex delimiter char) and then any 1 or more whitespaces (\s+) to replace with a backslash:

s = s.replace(/\/\s+/g, '')

Or, capture the forward slash with a capturing group (a pair of unescaped parentheses, (...)), and replace with a replacement backreference $1:

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

See the JS demo:

console.log("/abc/   spaces/   more spaces".replace(/\/\s+/g, '/'))console.log("/abc/   spaces/   more spaces".replace(/(\/)\s+/g, '$1'))

Remove special symbols and extra spaces and replace with underscore using the replace method

Your regular expression [^a-zA-Z0-9]\s/g says match any character that is not a number or letter followed by a space.

Remove the \s and you should get what you are after if you want a _ for every special character.

var newString = str.replace(/[^A-Z0-9]/ig, "_");

That will result in hello_world___hello_universe

If you want it to be single underscores use a + to match multiple

var newString = str.replace(/[^A-Z0-9]+/ig, "_");

That will result in hello_world_hello_universe