var regex_textBoxCleared = false;
function regex_clearTextBox() {
	if(!regex_textBoxCleared) { 
		$('regex_input').value = ""; 
		regex_textBoxCleared = true; 
	}
}
function regex_match(mode) {
	$('regex_output').style.display = "block";
	var regex = htmlentitiesregex($('regex_regex').value);
	var regexInput = htmlentities($('regex_input').value);
	var replaceWith = (mode == "r")? $('regex_string_replace').value : "<em>$1</em>";
	var flag = $('regex_flag').value;
	try {
		eval("regexInput = regexInput.replace(/(" + regex + ")/" + flag + ", \"" + replaceWith + "\");"); 
		regexInput = regexInput.replace(/<em><\/em>/gi, ""); // clean up useless <em></em>
		$('regex_output').innerHTML = "<pre>" + regexInput + "</pre>";
	} catch(e) { 
		$('regex_output').innerHTML = "Invalid Regular Expression, please double-check."; 
	}
}