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事件处理
以下的事件可由 JavaScript 发生: onBlur event handlerA 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 toExamplesxxx Examples to be supplied. onChange event handlerA 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 toExamplesxxx Examples to be supplied. onClick event handlerFor 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 tobutton, checkbox, radioButton, link, reset, submit ExamplesFor 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: <INPUT TYPE="button" VALUE="Calculate" onClick="compute(this.form)"> 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 handlerExecuted when input focus enters the field, either by tabbing in or by clicking but not selecting in the field. Applies toExamplesxxx Examples to be supplied. onLoad event handlerA 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="...">. Applies toExamplesxxx Examples to be supplied. See alsoonUnload event handler onMouseOver event handlerExecutes when the mouse pointer is over an object. You must return true if you want to set the window.status property with the onMouseOver event handler. Applies toExamplesBy default, the HREF value of an anchor displays in the status bar at the bottom of the Navigator when a user places the mouse pointer over the anchor. In the following example, the onMouseOver event handler provides the custom message "Click this if you dare." See onClick for an example of using onMouseOver when the anchor HREF attribute is set dynamically. onSelect event handler
A select event occurs when a user selects some of the text within a text or textArea field. The onSelect event handler executes JavaScript code when a select event occurs. Applies toExamplesxxx Examples to be supplied. onSubmit event handlerSpecifies the JavaScript code to run when a user attempts to submit a form. Return true to allow the form to be submitted; return false to prevent the form from being submitted.Applies toExamplesIn the following example, the onSubmit event handler evaluates the data being submitted to test if it is legal. If the data is legal, the form is submitted; otherwise, the form is not submitted. onUnload event handlerAn unload event occurs when you exit a document. The onUnload event handler executes JavaScript code when an unload event occurs. Use the onUnload event handler within either the <BODY> or the <FRAMESET> tags, for example, <BODY onUnload="...">. Applies toExamplesxxx Examples to be supplied. See alsoonLoad event handler 回目录 |
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