JSFiddle - React, Tailwind, and code Playground

HTML

<input type='text' id='spa' onkeyup='check()'><br>
 <input type='text' id='eng' onkeyup='check()'><br>
<input type='button' id='submit' value="Submit" disabled>

JavaScript

$("input[type=text]").keyup(function(){
    var count = 0, attr = "disabled", $sub = $("#submit"), $inputs = $("input[type=text]");  
    $inputs.each(function(){
        count += ($.trim($(this).val())) ? 1:0;
    });
    (count >= $inputs.length ) ? $sub.removeAttr(attr):$sub.attr(attr,attr);       
});