JavaScript Regular Expression OR Operator

Question

Saw a challenge on Twitter so I've been working my way through it, granted I am not the best with Regular Expressions. This is what I have so far:

var pass_regex = new RegExp(/^[a-z][A-Z][0-9]|[!@#$%^&*()_]+$/);

I am trying to match a password input that contains:

1 Lowercase Letter
1 Uppercase Letter
1 Digit OR Special Character

Where I am getting stuck is on the 'OR' part, I thought the pipe separator between [0-9] and my set of special characters would work but it doesn't seem to. Trying to better understand how you would use regular expressions to to check for 1 Digit OR 1 Special Character. Thank you in advance for any help provided.

The exact instruction from the challenge was "The password must contain a minimum of one lowercase character, one uppercase character, and one digit or special character." — mikes02
– mikes02, Commented Feb 3, 2015 at 1:51
for readability and maintainability, suggest to write the rules in separate units. passwd.match(/[a-z]/) && passwd.match(/[A-Z]/) && ( passwd.match(/0-9/) || passwd.match(/[!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]/) ) — user1375096
– user1375096, Commented Feb 3, 2015 at 1:55

Avinash Raj · Accepted Answer · 2015-02-03 01:57:14Z

2

Atleast one:

You need to use a positive lookahead based regex for checking multiple conditions.

^(?=.*?[A-Z])(?=.*?[a-z]).*?[\W\d].*

OR

^(?=.*?[A-Z])(?=.*?[a-z]).*?[!@#$%^&*()_\d].*

(?=.*?[A-Z]) Asserts that there must be atleast one uppercase letter.
(?=.*?[a-z]) Atleast one lowercase letter.
.*? non-greedy match of any character zero or more times.
If the above conditions are satisfied then match that corresponding string and also the string must contain atleast a single character from the given list [!@#$%^&*()_\d] . \d in this list matches any digit character.
.* matches the following zero or more characters.

DEMO

edited Feb 3, 2015 at 1:57

answered Feb 3, 2015 at 1:45

Avinash Raj

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6 Comments

mikes02 Over a year ago

I appreciate your time helping me with this, however, as I am not very good with RegEx it is difficult for me to comprehend what you have provided above, if you have the time, could you please explain?

Avinash Raj Over a year ago

for condition checking purpose, .* at the last is unnecesary but op says I am trying to match a password input that contains, that is he's trying to match the whole password. So here .* is must :)

mikes02 Over a year ago

Thank you for your quick help. Here's a quick test I setup:

var pass_regex = new RegExp(/^(?=.*?[A-Z])(?=.*?[a-z]).*?[!@#$%^&*()_\d].*/); 		if(!pass_regex.test(password.val())) 		{ 			alert('Invalid Password'); 			validated = false; 		}

But I am wondering, the password test Az1$ passes but I was trying to figure out an OR operator, meaning it should contain one digit OR one special character and this RegEx does not seem to handle that. Any ideas?

Avinash Raj Over a year ago

use var pass_regex = /^(?=.*?[A-Z])(?=.*?[a-z]).*?[!@#$%^&*()_\d].*/m; . Yep, Az1$ string satisfies the above condition of uppercase, atleast lowecase and a digit. So it got matched.

mikes02 Over a year ago

That seems to have done the trick, thank you. It appears that all that was changed was the addition of the 'm' character to the end, right? What exactly did that do to change the RegEx?

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