function httpRequest(url, func) {
	var http_request = false;
	
	if (window.XMLHttpRequest) { // Mozilla, Safari,...
		http_request = new XMLHttpRequest();
	} else if (window.ActiveXObject) { // IE
		try {
			http_request = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				http_request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
		}
	}
	
	if (!http_request) {
		alert('Giving up :( Cannot create an XMLHTTP instance');
		return false;
	}
	
	// 定義事件處理函數為 alterContents()
	http_request.onreadystatechange = function() {func(http_request);};
	http_request.open('GET', url, true);
	http_request.send(null);
}