JSFiddle - React, Tailwind, and code Playground

by Peter Hozák

HTML

<form id="myform">
    <label>A:<input type="text" id="a"/></label><br/>
    <label>B:<textarea id="b"></textarea></label>
    <input type="submit"/>
</form>

CSS

.invalid {
    background: #faa;
}

JavaScript

var validate = function(evt){
    // your custom code, e.g.:
    valid = true;
    if ($('#a').val() !== "a") {
        valid = false;
        $('#a').addClass("invalid");
    } else {
        $('#a').removeClass("invalid");
    }
    return valid;
}

$('#myform').change(validate);
$('#myform').submit(validate);