Validating fields

In this section, we will explore how to validate different types of fields manually, such as name, e-mail, website URL, and so on.

Matching a complete name

To get our feet wet, let's begin with a simple name field. It's something we have gone through briefly in the past, so it should give you an idea of how our system will work. The following code goes inside the script tags, but only after everything we have written so far:

function process_name() {
    var field = document.getElementById("name_field");
    var name = field.value;

    var name_pattern = /^(\S+) (\S*) ?\b(\S+)$/;

    if (name_pattern.test(name) === false) {
        alert("Name field is invalid");
        return false;
    }

    var res = name_pattern.exec(name);
    data.first_name = res[1];
    data.last_name = res[3];

    if (res[2].length > 0) {
        data.middle_name = res[2];
    }

    return true;
}

fns.push(process_name);

We get the name field in a similar way to how we got the form, then...