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, Feb 24 '16 at 20:36
convert your string to a RegExp object http://stackoverflow.com/questions/4589587/javascript-regular-expression-string-to-regex-object — phenxd, Feb 24 '16 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, Feb 24 '16 at 20:41

score 1 · Accepted Answer · edited May 23 '17 at 11:45

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 '17 at 11:45

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answered Feb 24 '16 at 20:54

Oriol

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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. – lowdegeneration Feb 24 '16 at 22:26
`word = 'Joe/Hugh'`? – Oriol Feb 24 '16 at 22:37
well to be specific, when dynamic "word" catches Chris then how can I get Joe/Hugh/ with regex automatically afterwards ... – lowdegeneration Feb 24 '16 at 22:41
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; });` – Oriol Feb 24 '16 at 23:05

score 0 · Answer 2 · answered Feb 24 '16 at 20:44

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

multiple regex match using javascript

2 Answers2