Availability

JavaScript 1.0

Synopsis

<input type="type"onchange="handler"> 
input.onchange

Description

The onchange property of an Input object specifies an event handler function that is invoked when the user changes the value displayed by a form element. Such a change may be an edit to the text displayed in Text, Textarea, Password, or FileUpload elements, or the selection or deselection of an option in a Select element. Note that this event handler is only invoked when the user makes such a change -- it is not invoked if a JavaScript program changes the value displayed by an element.

Also note that the onchange handler is not invoked every time the user enters or deletes a character in a text-entry form element. onchange is not intended for that type of character-by-character event handling. Instead, onchange is invoked when the user's edit is complete. The browser assumes that the edit is complete when keyboard focus is moved from the current element to some other element -- for example, when the user clicks on the next element in the form. See the HTMLElement.onkeypress reference page for character-by-character event notification.

The onchange event handler is not used by the Hidden element or by any of the button elements. Those elements -- Button, Checkbox, Radio, Reset, and Submit -- use the onclick event handler instead.

The initial value of this property is a function that contains the semicolon-separated JavaScript statements specified by the onchange attribute of the HTML tag that defined the object. When an event handler function is defined by an HTML attribute, it is executed in the scope of element rather than in the scope of the containing window.

In the Netscape 4 event model, the onchange handler function is passed an Event object as an argument. In the IE event model, no argument is passed, but the applicable Event object is available as the event property of the Window object that contains the element.

See Also

HTMLElement.onkeypress; Chapter 19; Event, EventListener, and EventTarget in the DOM reference section