Regular Expression to get a string between parenth

问题:

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

回答1:

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

回答2:

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));
}

回答3:

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]
  })

回答4:

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

Or \\(.+\\) for anything inside brackets

回答5:

Simple solution

Notice: this solution used for string that has only single \"(\" and \")\" like string in this question.

(\"I expect five hundred dollars ($500).\").match(/\\((.*)\\)/).pop();

Online demo (jsfiddle)

回答6:

To match a substring inside parentheses excluding any inner parentheses you may use

\\(([^()]*)\\)

pattern. See the regex demo.

In JavaScript, use it like

var rx = /\\(([^()]*)\\)/g;

Pattern details

• \\( - a ( char
• ([^()]*) - Capturing group 1: a negated character class matching any 0 or more chars other than ( and )
• \\) - a ) char.

To get the whole match, grab Group 0 value, if you need the text inside parentheses, grab Group 1 value:

var strs = [\"I expect five hundred dollars ($500).\", \"I expect.. :( five hundred dollars ($500).\"];
var rx = /\\(([^()]*)\\)/g;


for (var i=0;i<strs.length;i++) {
  console.log(strs[i]);

  // Grab Group 1 values:
  var res=[], m;
  while(m=rx.exec(strs[i])) {
    res.push(m[1]);
  }
  console.log(\"Group 1: \", res);

  // Grab whole values
  console.log(\"Whole matches: \", strs[i].match(rx));
}

回答7:

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