Javascript password validation using regex

Question

I have a problem with my password validation using regex on javascript. the criteria are :

have at least one or more letter(it can be upper case or lower case)
have at least one or more number
character length minimal 3 and maximal 30

I hope anyone can help me to solve this problem :)

var ch_pass = /^([0-9]+).([a-zA-Z]+).({3,30})$/;

You can easily check #3 by checking the value's .length. For #1 and #2, just use two regular expressions to check that the value contains a alpha and numeric character each. For example: var value = "YOUR INPUT", alpha = /[A-Za-z]/, numeric = /[0-9]/; if (value.length < 3 || value.length > 30 || !alpha.test(value) || !numeric.test(value)) { /* INVALID */ }. It's a lot easier to read/understand/maintain, in my opinion — Ian
– Ian, Commented Mar 5, 2014 at 19:36

anubhava · Accepted Answer · 2014-03-05 19:37:05Z

2

You can use lookahead like this:

var ch_pass = /^(?=.*?[0-9])(?=.*?[a-zA-Z]).{3,30}$/;

answered Mar 5, 2014 at 19:37

anubhava

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2 Comments

anubhava Over a year ago

Glad to know, can you mark the answer as accepted by clicking on tick mark on top-left of my answer.

anubhava Over a year ago

That is lazy vs non-lazy matching

ohmu · Accepted Answer · 2014-03-05 20:47:18Z

2

I wouldn't recommend trying to do this whole check in a single regular expression because it just over complicates it. Do each condition individually.

Has at least one letter:

var has_letters = (/[a-zA-Z]/).test(password);

Has at least one number:

var has_numbers = (/[0-9]/).test(password);

Has between 3 and 30 characters (inclusive):

var has_length = 3 <= password.length && password.length <= 30;

This can all be wrapped up into a function:

function is_password_valid(password) {
    var has_letters = (/[a-zA-Z]/).test(password);
    var has_numbers = (/[0-9]/).test(password);
    var has_length = 3 <= password.length && password.length <= 30;
    return has_letters && has_numbers && has_length;
}

Or if you prefer something more dense:

function is_password_valid(password) {
    return ((/[a-zA-Z]/).test(password)
        && (/[0-9]/).test(password)
        && password.length >= 3
        && password.length <= 30);
}

edited Mar 5, 2014 at 20:47

answered Mar 5, 2014 at 19:43

ohmu

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6 Comments

Ian Over a year ago

Not that it matters, but regex.test makes more sense to use, instead of .match() != null. And for #3, you left out the "maximum 30" part

ohmu Over a year ago

@Ian Thank you, I wasn't aware of .test().

Ian Over a year ago

Sorry, test is a method of a regular expression object. You'd use var alpha = /[a-zA-Z]/; and then alpha.test(password) - it returns a boolean if it matches or not

ohmu Over a year ago

@Ian I guess that's what I get for not double checking.

Ian Over a year ago

As a reference to you or anyone else: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… . And I'd read that page, especially the Description because of the quirk when using a global search. Your regexes don't do that, so it should be fine, but in case of future use

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