Check if string is a URL?

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urlBAK = function (msg) {


	var escaped = "";
	var ltPos = msg.indexOf("<");
	while (ltPos != -1) {
		escaped = msg.substring(0, ltPos)+"<"+msg.substring(ltPos+1);
		msg = escaped;
		ltPos = msg.indexOf("<");
	}


	var escaped = "";
	var ltPos = msg.indexOf(">");
	while (ltPos != -1) {
		escaped = msg.substring(0, ltPos)+">"+msg.substring(ltPos+1);
		msg = escaped;
		ltPos = msg.indexOf(">");
	}


	var url_begin = msg.indexOf("http://");
	if (url_begin == -1) {
		url_begin = msg.indexOf("www.");
	}
	if (url_begin == -1) {
		return msg;
	}

	var hilited = msg.substring(0, url_begin);
	hilited = urlBAK(hilited);
	var url_end = msg.indexOf(" ", url_begin);
	var urlstr = "";

	if (url_end == -1) {
		urlstr = msg.substring(url_begin);
	} else {
		urlstr = msg.substring(url_begin, url_end);
	}

	var urlref = urlstr;
	if (urlstr.indexOf("www.") == 0) {
		urlref = "http://"+urlstr;
	}

	var trailer = "";
	if (url_end != -1) {
		trailer = urlBAK(msg.substring(url_end));
	}

	hilited += "" + urlstr + "" + trailer;
	return hilited;

}

This function makes url’s as links in a given text… it can convert all…