For example, a button click is an event, as is giving focus to a form element. There is a specific set of events that Navigator recognizes. You can define Event handlers, scripts that are automatically executed when an event occurs.
In general, it is a good idea to define functions for your event handlers because:
Notice in this example the use of this.form to refer to the current form. The keyword this refers to the current object-in the above example, the button object. The construct this.form then refers to the form containing the button. In the above example, the onClick event handler is a call to the compute() function, with this.form, the current form, as the parameter to the function.
Events apply to HTML tags as follows:
If an event applies to an HTML tag, then you can define an event handler for it. In general, an event handler has the name of the event, preceded by "on." For example, the event handler for the Focus event is onFocus.
Many objects also have methods that emulate events. For example, button has a click method that emulates the button being clicked. Note: The event-emulation methods do not trigger event-handlers. So, for example, the click method does not trigger an onClick event-handler. However, you can always call an event-handler directly (for example, you can call onClick explicitly in a script).
|Event||Occurs when...||Event Handler|
|blur||User removes input focus from form element||onBlur|
|click||User clicks on form element or link||onClick|
|change||User changes value of text, textarea, or select element||onChange|
|focus||User gives form element input focus||onFocus|
|load||User loads the page in the Navigator||onLoad|
|mouseover||User moves mouse pointer over a link or anchor||onMouseOver|
|select||User selects form element's input field||onSelect|
|submit||User submits a form||onSubmit|
|unload||User exits the page||onUnload|
Example 4: a script with a form and an event handler attribute.
Example 4 page display.
Be sure to alternate double quotes with single quotes. Since event handlers in HTML must be enclosed in quotes, you must use single quotes to delimit arguments. For example<FORM NAME="myform">
Alternatively, you can escape quotes by preceding them by a backslash (\).