JSFiddle - React, Tailwind, and code Playground

HTML

<form onsubmit="return check_checkbox()">
<input type="checkbox" id="terms" unchecked/>Terms
<br /><br />
<button id="submit">
continue</button>
</form>

JavaScript

function check_checkbox() 
{
  if($('#terms').is(':checked')) {
  	return true;
  } else {
    alert("To proceed you must accept the terms.");
    return false;
  }
}