How to check for uppercase alphabets in an input string, using jQuery

Question

Hi, I am using following code snippet, but its not working :-(

    //First four characters of input Text should be ALPHABATES (Letters)

    if (($("#txtId").val()).length >= 4) {
        var firstFourChars = $("#txtId").val().substring(0, 4);
        var pattern = new RegExp('[^A-Z]');

        if (firstFourChars.match(pattern))
            isValid = true;
        else
            isValid = false;
    }

Answer 1

change /[^A-Z]/ to /^[A-Z]/

example :

var a = "ABCJabcd";
console.log(a.match(/^[A-Z]{4}/));

Answer 2

The regex should be /[^A-Z]{4}/ if you want to match the 4 lowercase characters.

Answer 3

Hi, you don't need to use substring(). Your regexp can do all the work for you. The RegExp you are using matches against characters that are NOT between A and Z. As Avinash said, ^[A-Z]{4} will match if your first 4 characters are uppercase. "^" at the beginning of your regexp tells that the following should be the beginning of the string. When placed inside square brackets, it reverts the range of characters you want to match.