I have a dynamic string like this which may look like:

69.43.202.97                 OR               ngs.pradhi.com

I want to validate these string contains only numbers, english alphabets and . . I want to validate this in front end using java script. I thought of using regular expression like this:

function validatePath() {

    var path = document.getElementById('server_path').value;

    path.match([a-z][0-9])  //or something like this

}

If the path is invalid despite of displaying the alert box I just want to show the error below the text field as soon as the user fills the server path. How can I do that?

My full javascript function looks like this:

function validatePath() {

    var path = document.getElementById('server_path').value;

    if (path.search(:) == -1){

        alert(Invalid server path);

    }

    else{

        var host_name = path.split(:)[0]

        if host_name.match(^[a-zA-Z0-9.]*$)) {}



    }

}