JSFiddle - React, Tailwind, and code Playground

HTML

<form id="contact-form1" action="/">
    <input type="text" id="contact-forename1" name="contact-forename">
    <input type="submit" id="contact-submit1" name="contact-submit">
</form>

JavaScript

$('#contact-form1').submit(submitForm("1"));

function submitForm(event, formId) {
    event.preventDefault();

    var forename = '#contact-forename' + formId;

    if (!$(forename).val()) {

        var string = 'Null field: ' + '#contact-forename' + formId;
        alert(string);

    } else {
        var string = 'Submitted field: ' + '#contact-forename' + formId;
        alert(string);
    }
    return false;
}