multiple regex match using javascript

Question

var wordsString="car/home/pencil,Joe/Hugh/Jack/Chris";
var word='home';
var pattern1=/^/+word;
var pattern2=/,/+word;
var pattern3 =/\//+word;

var matched = wordsString.match(pattern1+ /|/ +pattern2+ /|/ + pattern3 + /g/);

I want to match results from wordsString by using pattern1, pattern2, pattern3.

I need to match according to pattern1 or pattern2 or pattern3. But I get null.

Where is the problem?

Don't attempt to use the value of a variable until it has been assigned. And regex literals don't work like this. — Oriol
– Oriol, Commented Feb 24, 2016 at 20:36
convert your string to a RegExp object stackoverflow.com/questions/4589587/… — phenxd
– phenxd, Commented Feb 24, 2016 at 20:41
Are you just trying to match "home"? Whats wrong with /home/? is it that you want to use a variable to make the regexp? — Gabs00
– Gabs00, Commented Feb 24, 2016 at 20:41

Community · Accepted Answer · 2017-05-23 11:45:00Z

1

You can't concatenate regexp literals. However, you can concatenate strings and use them to build a regexp object:

var wordsString = "car/home/pencil,Joe/Hugh/Jack/Chris",
    word = 'home',
    escapedWord = RegExp.escape(word),
    patterns = ['^' + escapedWord, ',' + escapedWord, '/' + escapedWord],
    regex = new RegExp(patterns.join('|'), 'g'),
    matched = wordsString.match(regex);

RegExp.escape is needed in case word contains characters with special meaning in regular expressions. It has been proposed as a standard but has not been accepted yet, so you must define it manually using the code from here.

edited May 23, 2017 at 11:45

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answered Feb 24, 2016 at 20:54

Oriol

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4 Comments

lowdegeneration Over a year ago

I also a need pattern to catch "car/home/" or Joe/Hugh/...I mean I also need to catch 2 "/" with 2 words. How can I define it like "/" repeated 2 times and then get the words together.

Oriol Over a year ago

word = 'Joe/Hugh'?

lowdegeneration Over a year ago

well to be specific, when dynamic "word" catches Chris then how can I get Joe/Hugh/ with regex automatically afterwards ...

Oriol Over a year ago

Consider not using regex:

var wordsString = "car/home/pencil,Joe/Hugh/Jack/Chris", word = 'home', matched = wordsString.split(',').filter(function(str){ return str.split('/').indexOf(word) >= 0; });

Chris Hawkes · Accepted Answer · 2016-02-24 20:44:36Z

0

You cannot concatenate Regex's in JavaScript the way you are doing it, but you can concat strings that comprise a single regex. Don't escape the pipe symbol though, that is how it matches this or that.

var one = "test"
var two = "this"

var regex = new RegExp("^(first|" + one + "|" + two + ")")

var match = regex.test("this"); // matches
var noMatch = regex.test("no match"); // does not match

answered Feb 24, 2016 at 20:44

Chris Hawkes

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