gistfile1.js

// html email code transformation
// See http://www.awflasher.com/jsmail
function HtmlEncode( s )
{
	var result = "";
	for (var j = 0; j < s.length; j++ ) {
		// Encode 25% of characters
		if (Math.random() < 0.25 
		|| s.charAt(j) == ':' 
		|| s.charAt(j) == '@'
		|| s.charAt(j) == '.') { 
			var charCode = s.charCodeAt(j);
			result += "&#";
			result += charCode;
			result += ";"
		} else {
			result += s.charAt(j);
		}
	}
	return result;
}

function UrlEncode( s ) 
{
	var HEX = "0123456789ABCDEF";
	var encoded = "";
	for (var i = 0; i < s.length; i++ ) {
		// Encode 25% of characters
		if (Math.random() < 0.25) { 
			var charCode = s.charCodeAt(i);
			encoded += "%";
			encoded += HEX.charAt((charCode >> 4) & 0xF);
			encoded += HEX.charAt(charCode & 0xF);
		} else {
			encoded += s.charAt(i);
		}
	} // for
	return encoded;
}
function Obfuscate()
{
	var plaintext = document.TheForm.F1.value;
	var result = "<a href='";
	result += HtmlEncode("mailto:" + UrlEncode(plaintext) ) 
	result += "'>"
	result += HtmlEncode(plaintext) 
	result += "</a>";
	document.TheForm.F2.value = result;
    if (document.all) {
	    document.all.RESULT.innerHTML = "æç»ææ: " + result;
    } else {
	    document.getElementById("result").innerHTML = "æç»ææ: " + result + " ï¼æ³¨æè§å¯ç¶ææ ï¼è¿å¯æ¯æ åçmailtoé¾æ¥å¦ï¼";
    }
	return false; /* Privacy note: returning false prevents the browser from posting your email address! */
};

When you put some string together, you'd better do like this:
str = [];
str.push(str1);
str.push(str2);
str = str.join('');