- Javascript in CGI scripts
<form onsubmit=return(isRequired(document.checklinkForm)) name=checklinkForm ...>
</form>

//Check for the required fields
function isRequired (thisForm) {
    var empty = false;
    // URI
    if (isEmpty(thisForm.uri) || (thisForm.uri.value == "http://")) {
        alert("The URL field is required. Please fill it in.");
        thisForm.uri.select();
        thisForm.uri.focus();
        empty = true;
    }
    // verify URL format
    if ((empty == false) && (verifyURI(thisForm.uri) == false)) {
        alert("Invalid URL submitted. Please submit a valid URL.");
        thisForm.uri.select();
        thisForm.uri.focus();
        empty = true;
    }
    return (!(empty));
}