JSFiddle - React, Tailwind, and code Playground

HTML

<form name="myform" method="post">
<input onkeyup="checkFormsValidity();" id="input_id" type="text" name="input_name" value=""/>
<input type="submit" name="submit_name" value="OK" class="submit_class" id="SubmitButton"/>
</form>

CSS

input[type='submit']:disabled{
	color:red;
}

JavaScript

var sbmtBtn = document.getElementById("SubmitButton");
sbmtBtn.disabled = true; 

function checkFormsValidity(){
var myforms = document.forms["myform"];   
	if (myforms.checkValidity()) {
		sbmtBtn.disabled = false;
	} else {
		sbmtBtn.disabled = true;
	}
}