JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <p>Some text Some text Some text Some text Some text Some text Some text Some text Some text Some text Some text Some text Some text </p>
    <input type="submit" value="click" id="color"/>
</body>

CSS

body{color:blue;}

JavaScript

$('#color').on('click', function(){
    if($('body').css('color')!='black')
    {
        $('body').css('color','black');
    }
});