HTML encode and decode in JavaScript.

html_util.js

function html_encode(str) {
	var s = "";
	if (str.length == 0) return "";
	s = str.replace(/&/g, "&");
	s = s.replace(/</g, "&lt;");
	s = s.replace(/>/g, "&gt;");  
	s = s.replace(/\'/g, "&#39;");
	s = s.replace(/\"/g, "&quot;");
	return s;
}

function html_decode(str) {   
	var s = "";   
	if (str.length == 0) return "";
	s = str.replace(/&amp;/g, "&");
	s = s.replace(/&lt;/g, "<");
	s = s.replace(/&gt;/g, ">"); 
	s = s.replace(/&#39;/g, "\'");   
	s = s.replace(/&quot;/g, "\""); 
	return s;   
}