JSFiddle - React, Tailwind, and code Playground

HTML

<form action="" method="post" id="subnewtopicform" />
                
                    Title:
                    <input type="text" name="title">
    
    <br/>
    
                    Description:
                    <textarea name="description" required onkeyup="if(this.textLength != 0) {subnewtopic.disabled = false} else {subnewtopic.disabled = true}"></textarea> 
    
    <br/>
                    Category:
    <ul class="list:category categorychecklist form-no-clear" id="categorychecklist">
    
    <li id="category-19"><label class="selectit"><input type="radio" id="in-category-19" name="category" value="19" required> Animation</label></li>
    
    <li id="category-20"><label class="selectit"><input type="radio" id="in-category-20" name="category" value="20" required> Anime</label></li>
    
    	</ul>
    
                    <input type="submit" value="Submit Topic" class="button-primary" name="subnewtopic" id="subnewtopic" disabled="disabled" /> 
    
                </form>

JavaScript

(function() {
    $('form > input').keyup(function() {

        var empty = false;
        $('form > input').each(function() {
            if ($(this).val() == '') {
                empty = true;
            }
        });

        if (empty) {
            $('#submit').attr('disabled', 'disabled');
        } else {
            $('#submit').removeAttr('disabled');
        }
    });
})()