How can i clear the TextBox Value and others?

How can i clear the textbox in the my onClick function?

	var Observable = require("FuseJS/Observable");
	var items = Observable();
	var t;
	function onClick(sender) {
		items.add({txt: t});
		t = "";
	function onValueChange(e) {
			t = e.value;
	module.exports = {
		items: items,
		onClick: onClick,
		onValueChange: onValueChange

		<Text Value="Connection..." Dock="Top"/>

		<ScrollView Dock="Top">
				<Each Items="{items}">
						<Text TextWrapping="Wrap" Dock="Top" Value="{txt}"/>

		<DockPanel Dock="Bottom">
			<TextBox ux:Name="tb" PlaceholderText="Text..." Width="250" Dock="Left" Value="" ValueChanged="{onValueChange}">
			<Basic.Button Text="Send" Dock="Right">
					<Callback Handler="{onClick}"/>

I chose the wrong way. Next changes working fine:

var message =  Observable("");
function onClick(sender) {
		items.add({txt: message.value});
		message.value = "";
<TextInput PlaceholderText="Text..." Width="250" Dock="Left" Value="{message}">