How can i clear the TextBox Value and others?

General
1

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

<App>
	<JavaScript>
	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
	};
	</JavaScript>

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

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

		<DockPanel Dock="Bottom">
			<TextBox ux:Name="tb" PlaceholderText="Text..." Width="250" Dock="Left" Value="" ValueChanged="{onValueChange}">
			</TextBox>
			<Basic.Button Text="Send" Dock="Right">
				<Clicked>
					<Callback Handler="{onClick}"/>
				</Clicked>
			</Basic.Button>
		</DockPanel>
	</DockPanel>
</App>
2

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}">