var kzTwitter = {};

kzTwitter.addEventListener = function(target, type, callback)
{
	if (target) {
		if (document.addEventListener) {	// W3C DOM 2
			target.addEventListener(type, callback, false);
		} else if (document.attachEvent) {	// Internet Explorer
			target.attachEvent('on' + type, callback);
		}
	}
}

kzTwitter.init = function()
{
	var targets = ['block', 'center'];
	
	for (var i = 0; i < targets.length; i ++) {
		var elm = document.getElementById('tw_textarea_' + targets[i]);
		var label = document.getElementById('tw_counter_' + targets[i]);
		if (elm && label) {
			var handler = function(elm, label) {
				var el = elm;
				var lb = label;
				
				kzTwitter.addEventListener(elm, 'keyup', function(e) {
					lb.innerHTML = 140 - el.value.length;
				});
			}(elm, label);
		}
	}
}

// Attaches the 'onload' event listener to window
kzTwitter.addEventListener(window, 'load', kzTwitter.init);