CODEWITHSUNDEEP
javascriptregex
TianRB
TianRB

Reputation: 691

How can I create a regular expression that accepts at least one lowercase and one digit?

This expression must adhere to specific rules:

1.- Between 2 and 8 characters total.
2.- Start with uppercase.
3.- Contain both lowercase and digits.

The first and second should be easy, but I can't get the third one to work.

This is the expression I came up with 

([A-Z]+[A-Za-z0-9]*){2,8}

But it returns incorrect responses. Regular expressions are far from my forte, and this is the first time I had to use them outside of class.

This is my code, if it helps 

    var expresion = /([A-Z]+[A-Za-z0-9]*){2,8}/;
    var re = new RegExp(expresion); 
    var t = $('#code').val(); 
    if (re.test(t)) { 
        console.log(t+' works');
    } else {
        console.log(t+' not working');
    }

Upvotes: 0

Views: 48

Answers (2)

Amadan
Amadan

Reputation: 198324

This should fit your literal requirements (however, as comments state, they don't really make sense):

^(?=.{2,8}$)(?=.*[0-9])(?=.*[a-z])[A-Z][a-zA-Z0-9]*$

First, you need to anchor your match with ^ (start of string) and $; otherwise you can just be picking up a matching substring, which will mess up your requirements.

Second, we use lookahead to validate several individual points: the string contains between 2 and 8 characters before it ends, the string contains a digit.

Third, we use the character classes to validate that it starts with an uppercase, and continues with a mix of uppercase, lowercase and digits.

EDIT: Forgot the lowercase requirement, thanks nnnnnn. And you are right, your version is better.

Upvotes: 1

dawg
dawg

Reputation: 103744

Use look aheads that comport to each condition:

/^(?=[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.{2,8}$)(.*)/m

Demo

(As stated in comments, your target pattern is a minimum of 3 characters with the other conditions...)

Upvotes: 1

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