JSFiddle - React, Tailwind, and code Playground

HTML

<form method="post" action="/index" onsubmit="return validateBuyForm();">
    <input id="agreeToTerms" name="agreeToTerms" type="checkbox" /> I agree<br />
    <input value="Buy that stuff!!" id="pay" type="submit" />
</form>

JavaScript

window.validateBuyForm = function() {
    alert('we are validating!!');
    return false;
}