Generating strings from regular expression in JavaScript

Question

I think it can be done by generating strings using brute force and then try to match them to the supplied regex and printing if match.

But is there a better way to do this?

Regex are used to test if a string matches a pattern. I am aware of that. I thought it would be interesting to do it the way around.

Solution 1

If you're using JavaScript, there's Randexp which generates random strings that match a given regex.

Releases for browser

Solution 2

Use randexp.js, it does exactly what you want:

console.log(new RandExp(/^([a-zA-Z]){5}([0-9]){4}([a-zA-Z]){1}$/).gen());
console.log(new RandExp(/^[0-9]{4}$/).gen());
console.log(new RandExp(/^[0-9,A-Z]{4}$/).gen());
console.log(new RandExp(/^([A-Z]){5}([0-9]){4}([A-Z]){1}$/).gen());

<script src="https://github.com/fent/randexp.js/releases/download/v0.4.3/randexp.min.js"></script>

Comments

[Sjoerd]

Possible duplicate of Generate a random string based on a regular expression

[Dave Newton]

Higher Order Perl has a section discussing this problem. It's worth reading for other reasons, too.

[Sikshya Maharjan]

What's the problem you're trying to solve, what's the question?

[Anderson Green]

Randexp generates only one random string from a regex. To generate every possible match, you can use genexp.js instead.