Home » Javascript » Regular Expression to get a string between parentheses in Javascript

Regular Expression to get a string between parentheses in Javascript

Posted by: admin November 29, 2017 Leave a comment

Questions:

I am trying to write a regular expression which returns a string which is between parentheses. For example: I want to get the string which resides between the strings “(” and “)”

I expect five hundred dollars ($500).

would return

$500

Found Regular Expression to get a string between two strings in Javascript

But I’m new with regex. I don’t know how to use ‘(‘, ‘)’ in regexp

Answers:

You need to create a set of escaped (with \) parentheses (that match the parentheses) and a group of regular parentheses that create your capturing group:

var regExp = /\(([^)]+)\)/;
var matches = regExp.exec("I expect five hundred dollars ($500).");

//matches[1] contains the value between the parentheses
console.log(matches[1]);

Breakdown:

  • \( : match an opening parentheses
  • ( : begin capturing group
  • [^)]+: match one or more non ) characters
  • ) : end capturing group
  • \) : match closing parentheses

Here is a visual explanation on RegExplained

Questions:
Answers:

Try string manipulation:

var txt = "I expect five hundred dollars ($500). and new brackets ($600)";
var newTxt = txt.split('(');
for (var i = 1; i < newTxt.length; i++) {
    console.log(newTxt[i].split(')')[0]);
}

or regex (which is somewhat slow compare to the above)

var txt = "I expect five hundred dollars ($500). and new brackets ($600)";
var regExp = /\(([^)]+)\)/g;
var matches = txt.match(regExp);
for (var i = 0; i < matches.length; i++) {
    var str = matches[i];
    console.log(str.substring(1, str.length - 1));
}

Questions:
Answers:

Ported Mr_Green’s answer to a functional programming style to avoid use of temporary global variables.

var matches = string2.split('[')
  .filter(function(v){ return v.indexOf(']') > -1})
  .map( function(value) { 
    return value.split(']')[0]
  })

Questions:
Answers:

For just digits after a currency sign : \(.+\s*\d+\s*\) should work

Or \(.+\) for anything inside brackets

Questions:
Answers:
var str = "I expect five hundred dollars ($500) ($1).";
var rex = /$\d+(?=\))/;
alert(rex.exec(str));

Will match the first number starting with a $ and followed by ‘)’. ‘)’ will not be part of the match. The code alerts with the first match.

var str = "I expect five hundred dollars ($500) ($1).";
var rex = /$\d+(?=\))/g;
var matches = str.match(rex);
for (var i = 0; i < matches.length; i++)
{
    alert(matches[i]);
}

This code alerts with all the matches.

References:

search for “?=n”
http://www.w3schools.com/jsref/jsref_obj_regexp.asp

search for “x(?=y)”
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/RegExp