javascript, regex parse string content in curly brackets

Question

i am new to regex. I am trying to parse all contents inside curly brackets in a string. I looked up this post as a reference and did exactly as one of the answers suggest, however the result is unexpected.

Here is what i did

var abc = "test/abcd{string1}test{string2}test" //any string
var regex = /{(.+?)}/
regex.exec(abc) // i got ["{string1}", "string1"]
             //where i am expecting ["string1", "string2"]

i think i am missing something, what am i doing wrong?

update

i was able to get it with /g for a global search

var regex = /{(.*?)}/g
abc.match(regex) //gives ["{string1}", "{string2}"]

how can i get the string w/o brackets?

Mike Samuel · Accepted Answer · 2012-03-20 18:09:57Z

33

"test/abcd{string1}test{string2}test".match(/[^{}]+(?=\})/g)

produces

["string1", "string2"]

It assumes that every } has a corresponding { before it and {...} sections do not nest. It will also not capture the content of empty {} sections.

answered Mar 20, 2012 at 18:09

Mike Samuel

121k30 gold badges230 silver badges255 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Kash Over a year ago

This is good. But you do not need to escape the closing brace. /[^{}]+(?=})/g

AuthorProxy Over a year ago

How do the same with this braces? [ ]

Mike Samuel Over a year ago

@AuthorProxy, to include [ or ] in a character set, escape them. [\[\]] is a character set with only the square brackets.

AuthorProxy Over a year ago

@MikeSamuel it doesn't work, check at any online regexp

Mike Samuel Over a year ago

@AuthorProxy I did. /[\[\]]+/.exec('a[[]]b')[0] === '[[]]' is true in JS.

ZER0 · Accepted Answer · 2012-03-20 18:09:06Z

4

var abc = "test/abcd{string1}test{string2}test" //any string
var regex = /{(.+?)}/g
var matches;

while(matches = regex.exec(abc))
    console.log(matches);

answered Mar 20, 2012 at 18:09

ZER0

25.5k5 gold badges53 silver badges57 bronze badges

Comments

nicosantangelo · Accepted Answer · 2012-03-20 18:06:35Z

3

Try this:

var abc = "test/abcd{string1}test{string2}test" //any string
var regex = /{(.+?)}/g //g flag so the regex is global
abc.match(regex) //find every match

a good place to read about Regex in javascript is here, and a nice place to test is here

good luck!

answered Mar 20, 2012 at 18:06

nicosantangelo

13.8k3 gold badges35 silver badges47 bronze badges

2 Comments

Kash Over a year ago

I don't think g would make a difference here. It is not getting the second match (string2) because it is calling exec only once.

nicosantangelo Over a year ago

@Kash you're right, but I called match, and without the g, it will return ["{string1}", "string1"]

Community · Accepted Answer · 2017-05-23 11:53:49Z

1

Nothing wrong. But you'll need to look at your capturing groups (the second element in the array) to get the content you wanted (you can ignore the first). To get all occurences, it's not enough to run exec once, you'll need to loop over the results using match.

Edit: nevermind that, afaik you can't access capturing groups with match. A simpler solution would be using a positive lookahead, as Mike Samuel suggested.

edited May 23, 2017 at 11:53

CommunityBot

11 silver badge

answered Mar 20, 2012 at 18:07

mgibsonbr

22.1k7 gold badges73 silver badges115 bronze badges

Comments

jfriend00 · Accepted Answer · 2012-03-20 18:14:37Z

1

This result:

["{string1}", "string1"]

is showing you that for the first match, the entire regex matched "{string1}" and the first capturing parentheses matched "string1".

If you want to get all matches and see all capturing parens of each match, you can use the "g" flag and loop through, calling exec() multiple times like this:

var abc = "test/abcd{string1}test{string2}test"; //any string
var regex = /{(.+?)}/g;
var match, results = [];
while (match = regex.exec(abc)) {
    results.push(match[1]);   // save first captured parens sub-match into results array
}

// results == ["string1", "string2"]

You can see it work here: http://jsfiddle.net/jfriend00/sapfm/

edited Mar 20, 2012 at 18:14

answered Mar 20, 2012 at 18:05

jfriend00

711k104 gold badges1.1k silver badges1k bronze badges

3 Comments

jbabey Over a year ago

assignment in a condition... not my cup of tea.

jfriend00 Over a year ago

It's an efficient way to do this type of loop and somewhat common for this exact purpose. I would generally avoid it too, except in this type of case. You can take a couple more lines of code to accomplish the same thing without it if you want.

MengQi Han Over a year ago

thanks for the explanation, i was wondering why the same string appeared twice. thank you!

rabia yılmaz · Accepted Answer · 2021-12-08 06:42:15Z

1

try this for file

const fs = require('fs');

fs.readFile('logs.txt', function(err, data) {
if(err) throw err;
const paragraph = "'" + data + "'";
const regex = /\d+\<;>\S+\<;>(\d+)\<;/g;
const found = paragraph.match(regex);

console.log(found);
})

answered Dec 8, 2021 at 6:42

rabia yılmaz

512 bronze badges

Collectives™ on Stack Overflow

javascript, regex parse string content in curly brackets

6 Answers 6

5 Comments

Comments

2 Comments

Comments

3 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

5 Comments

Comments

2 Comments

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related