JSFiddle - React, Tailwind, and code Playground
HTML
<input type="checkbox" checked="checked" id="checky"><a href="#">terms and conditions</a>
<input type="submit" id="postme" value="submit">
JavaScript
$('#checky').click(function(){
if($(this).checked == false){
$('#postme').attr("disabled","disabled");
}
else
$('#postme').removeAttr('disabled');
});