<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.8.3.js'></script>
<script type='text/javascript'>
$(document).ready(function() {
var $text = $("textarea.textarea"),
$btn = $("input.submit");
$(document).on("click focus", function(e) {
if (!$text.is(e.target) && !$btn.is(e.target) && $text.val() == "") {
$btn.hide();
}
else {
$btn.show();
}
});
});
</script>
</head>
<body>
<div class="wrapper">
<textarea class="textarea"></textarea>
<input type="submit" class="submit" value="submit" />
</div>
</body>
</html>
The code above is rendered as follows:
【textarea】
