JavaScript/ Alphanumeric validation not working

Question

I have this reg ex for alphanumeric validation that I got from this post but it is not working with this function (I have a similar function for email and it works)

 function checkName(field) {

        var x = document.getElementById(field).value;
        var y = /^[a-z0-9]+$/i;
        //var z = /^[0-9]*$/;

        if (x == "" || !x.match(y) ) {
            alert("Invalid character");

            if (x.length <= 2 || x.length >= 15) {
                alert("Insert a name between 3 and 15 characters");
            }

            return false;
        }

    }

If I write some string/name I get both alerts. Can someone tell me what is wrong with this function?

Answer 1

Below is the approach for alphanumeric validation:

  function checkName(field) { var x = document.getElementById(field).value; if (x.length <= 2 || x.length >= 15) { alert("Insert a name between 3 and 15 characters"); return false; } var y = /^[0-9a-zA-Z]+$/; if (x == "" || !x.match(y) ) { alert("Invalid character"); return false; } alert("ALL OK"); return true; } 

 <input type="text" id="textName" /> <button onClick="checkName('textName');">Check</button> 

The Regex check for capital and small alphabets and numbers, and also checks for the length.

Answer 2

Your code works for me

 function checkName(field) {
        console.log(field);
        var x = field;
        var y = /^[a-z0-9]+$/i;
        if (x == "" || !x.match(y) ) {
            console.log("Invalid character");
        }
        if (x.length <= 2 || x.length >= 15) {
            console.log("Insert a name between 3 and 15 characters");
        }
    }
//valid
checkName('testdskfjskdlf');
//invalid
checkName('slkjf*%');
//too long
checkName('jjjjjjjjjjjjjjjjjjjjjjjjjjj');