Programming ASP .NET

Postback Versus Non-Postback Events

Postback events cause the form to be posted back to the server immediately. These include click-type events, such as Button.Click. In contrast, many events, typically change events, are considered non-postback because the event is not posted back to the server immediately. Instead, these events are cached by the control until the next time a post occurs. Controls with non-postback events can be forced to behave in a postback manner by setting their AutoPostBack property to true.

Table 3-3 summarizes the controls with postback and non-postback events.

Table 3-3. Controls with postback and non-postback events

Postback	Non-postback
Button	CheckBox
Calendar	CheckBoxList
DataGrid	DropDownList
DataList	ListBox
ImageButton	RadioButtonList
LinkButton	RadioButton
Repeater	TextBox