事件处理

以下的事件可由 JavaScript 发生:

onBlur onChange onClick onFocus onLoad onMouseOver onSelect onSubmit onUnload

onBlur event handler

A blur event occurs when a text or textArea field on a form loses focus. The onBlur event handler executes JavaScript code when a blur event occurs.

Applies to

selection, text, textArea

Examples

xxx Examples to be supplied.

onChange event handler

A change event occurs when a selection, text, or textArea field loses focus and its value has been modified. The onChange event handler executes JavaScript code when a change event occurs.

Use the onChange event handler to validate data after it is modified by a user.

Applies to

selection, text, textArea

Examples

xxx Examples to be supplied.

onClick event handler

For button or radioButton, JavaScript code to run when a button is clicked. For checkbox, JavaScript code to run when user checks or unchecks an item.

Applies to

button, checkbox, radioButton, link, reset, submit

Examples

For example, suppose you have created a JavaScript function called compute(). You can execute the compute() function when the user clicks a button by calling the function in the onClick event handler, as follows:

In the above example, the keyword this refers to the current object; in this case, the Calculate button. The construct this.form refers to the form containing the button.

For another example, suppose you have created a JavaScript function called pickRandomURL() that lets you select a URL at random. You can use the onClick event handler of an anchor to dynamically specify a value for the HREF attribute of the anchor, as shown in the following example:

In the above example, the onMouseOver event handler specifies a custom message for the Navigator status bar when the user places the mouse pointer over the Go! anchor. As this example shows, you must return true to set the window.status property in the onMouseOver event handler.

onFocus event handler

Executed when input focus enters the field, either by tabbing in or by clicking but not selecting in the field.

Applies to

selection, text, textArea

Examples

xxx Examples to be supplied.

onLoad event handler

A load event occurs when Navigator finishes loading a window or all frames within a FRAMESET. The onLoad event handler executes JavaScript code when a load event occurs.

Use the onLoad event handler within either the <BODY> or the <FRAMESET> tag, for example, <BODY onLoad="...">.