JSFiddle - React, Tailwind, and code Playground

HTML

<input type='text' id='spa' class='test'>
<br>
<input type='text' id='eng' class='test'>
<br>
<input type='button' id='submit' disabled>

JavaScript

$(".test").each(function () {
    $(this).keyup(function () {
        $("#submit").prop("disabled", CheckInputs());
    });
});

function CheckInputs() {
    var valid = false;
    $(".test").each(function () {
        if (valid) { return valid; }
        var input = $.trim($(this).val());
        valid = !input;
    });
    return valid;
}