Simple AJAX Library

/*
 * AJAX Library
 * Created November 26, 2010
 * Updated January 28, 2011
 * Released into the public domain by Josh Atkins
 */
 
function ajax() {
	this.ajaxObject                    = new XMLHttpRequest() || new ActiveXObject('Microsoft.XMLHTTP');
	var replace_html                   = false;
	this.ajaxObject.onreadystatechange = function() {
		if(this.readyState==4&&this.status==200) {	
			if(replace_html) {
				if(document.getElementById(replace_html).value)
					document.getElementById(replace_html).value     = this.responseText;
				else
					document.getElementById(replace_html).innerHTML = this.responseText;
			}
		}
	};
	ajax.prototype.sendRequest = function(method, uri, async, data, replace_html_element) {
		replace_html = replace_html_element;
		this.ajaxObject.open(method.toUpperCase(), uri + (method.toLowerCase() == 'get' ? '?' + data : ''), async);
		this.ajaxObject.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')
		this.ajaxObject.send(method.toLowerCase() == 'get' ? '' : data);
	};
}