Remove all spaces before and after parentheses

问题

I would like to remove one or more spaces before and after any parentheses. Following this post where the issue has been solved for PHP with the following regex

(?<=[([]) +| +(?=[)\]])

now I would like to do the same in Javascript but Javascript regex engine does not have the same lookahead and lookbehind as PHP. I managed to make the following regex at least work in Javascript but it removes all spaces:

?![([]) +| +(?=[)\]])

See Regex101 test.

Given string:

This is ( a sample     ) [           string ] to play with

Expected result:

This is (a sample) [string] to play with

回答1:

You may use capturing groups instead and replace with their placeholders to restore the bracket/parentheses in the result:

.replace(/([([])\s+|\s+([)\]])/g, "$1$2");

See the regex demo

Details

([([])\s+ - Group 1 capturing either a ( or a [ (referred to with $1 from the string replacement pattern) and then 1+ whitespaces
| - or
\s+([)\]]) - 1+ whitespaces followed with a ) or ] captured into Group 2 (referred to with $2 from the string replacement pattern)

JS demo:

var strs = ['This is ( a sample ) [ string ] to play with', 
            'This is ( a sample     ) [           string] to play with'];
var rx = /([([])\s+|\s+([)\]])/g;
for (var s of strs) {
  console.log(s+ " =>\n"+ s.replace(rx, "$1$2"));
}

回答2:

You can try this:

function Do(){
    console.log(document.querySelector("input").value
        .replace(/\s*?\s([\[\(])\s*/g, " $1").replace(/\s*([\)\]])(\s?)\s*/g, "$1$2"));
}

<b>Type Your String Here:</b>
<input type='text' style='width:300px' value="This is   (    a sample  )    [         string  ]   to play with"/>

<input type='button' onclick="Do();" value="Start!"/>

回答3:

You achieve this by using Positive lookaheads and a simple replace.

.replace(/(?<=[\(|\[])\s+|\s+(?=[\]|\)])/g, '');

ex.

const currentString = 'This is ( a sample     ) [           string ] to play with';
const regex = /(?<=[\(|\[])\s+|\s+(?=[\]|\)])/g;

console.log(currentString.replace(regex, ''));

来源：https://stackoverflow.com/questions/52188557/remove-all-spaces-before-and-after-parentheses

标签

javascript

regex