The event object is valid only when an event occurs.
Some Properties of the event only make sense for specific events. For example, the fromelement and toelement attributes only make sense for onmouseover and onmouseout events.
Example
The following example checks whether the mouse is clicked on the link. If the Shift key is pressed, the link jump will be canceled.
Code <HTML>The following example shows the current position of the mouse on the status bar.
Code <body onmousemove = "window. Status = 'X = '+ window. event. x + 'y =' + window. event. Y">
Attribute:
Altkey, button, Member, clientx, clienty, ctrlkey, fromelement, keycode, offsetx, offsety, propertyname, returnvalue, screenx, screeny, delimiter, srcelement, srcfilter, toelement, type, X, Y
1. altkey
Description:
Check the status of the Alt key.
Syntax:
Event. altkey
Possible values:
When the Alt key is pressed, the value is true; otherwise, the value is false. Read-only.
2. Button
Description:
Check the pressed mouse key.
Syntax:
Event. Button
Possible values:
0 without buttons
1 left click
2. Right-click
3. Press the Left or Right key.
4. Press the intermediate key
5. Press the left and intermediate keys.
6. Right-click and select intermediate key.
7. Press all keys
This attribute is only used for onmousedown, onmouseup, and onmousemove events. For other events, 0 (such as onclick) is returned regardless of the mouse status ).
3. cancelbubble
Description:
Checks whether events of the upper layer are controlled.
Syntax:
Event. cancelbubble [= cancelbubble]
Possible values:
This is a read/write Boolean value:
True is not controlled by the event of the parent layer.
False allows the event to be controlled by the upper-layer element. This is the default value.
Example:
The followingCodeThis section demonstrates how to cancel the showsrc () function triggered by event onclick on the upper-Layer Element (body) if the Shift key is also pressed when The onclick function is clicked on the image.
4. clientx
Description:
Returns the X coordinate of the mouse in the client area of the window.
Syntax:
Event. clientx
Note:
This is a read-only attribute. This means that you can only use it to get the current position of the mouse, but you cannot use it to change the position of the mouse.
5. clienty
Description:
Returns the Y coordinate of the mouse in the client area of the window.
Syntax:
Event. clienty
Note:
This is a read-only attribute. This means that you can only use it to get the current position of the mouse, but you cannot use it to change the position of the mouse.
6. ctrlkey
Description:
Check the status of the ctrl key.
Syntax:
Event. ctrlkey
Possible values:
When the ctrl key is pressed, the value is true; otherwise, the value is false. Read-only.
7. fromelement
Description:
Detects the elements that the mouse leaves when the onmouseover and onmouseout events occur. Reference: 18. toelement
Syntax:
Event. fromelement
Note:
This is a read-only attribute.
8. keycode
Description:
Detects the internal code corresponding to the keyboard event.
This attribute is used for onkeydown, onkeyup, and onkeypress events.
Syntax:
Event. keycode [= keycode]
Possible values:
This is a readable value and can be any Unicode keyboard internal code. If no keyboard event is triggered, the value is 0.
9. offsetx
Description:
Checks the horizontal coordinates of the mouse position relative to the trigger event object.
Syntax:
Event. offsetx
10. offsety
Description:
Check the vertical coordinates of the mouse position relative to the trigger event object
Syntax:
Event. offsety
11. propertyname
Description:
Sets or returns the name of an element's changed attribute.
Syntax:
Event. propertyname [= sproperty]
Possible values:
Sproperty is a string that specifies or returns the name of the attribute changed by the element that triggers the event.
This attribute can be read and written. No default value.
Note:
You can use the onpropertychange event to obtain the value of propertyname.
Example:
The following example uses the onpropertychange event to display the value of propertyname in a dialog box.
Function changecssprop (){
Btnstyleprop. style. backgroundcolor = "Aqua ";
}
</SCRIPT>
</Head>
<Body>
<P> the event object property propertyname is
Used here to return which property has been
Altered. </P>
<Input type = button id = btnprop onclick = "changeprop ()"
Value = "click to change the value property of this button"
Onpropertychange = 'alert (event. propertyname + "property has changed value") '>
<Input type = button id = btnstyleprop
Onclick = "changecssprop ()"
Value = "click to change the CSS backgroundcolor property of this button"
Onpropertychange = 'alert (event. propertyname + "property has changed value") '>
</Body>
12. returnvalue
Description:
Set or check the value returned from the event
Syntax:
Event. returnvalue [= Boolean]
Possible values:
The value in the true event is returned.
False: the default operation of events on the source object is canceled.
For examples, see the beginning of this article.
13. screenx
Description:
Detects the horizontal position of the mouse relative to the user's screen
Syntax:
Event. screenx
Note:
This is a read-only attribute. This means that you can only use it to get the current position of the mouse, but you cannot use it to change the position of the mouse.
14. screeny
Description:
Detect the vertical position of the mouse relative to the user's screen
Syntax:
Event. screeny
Note:
This is a read-only attribute. This means that you can only use it to get the current position of the mouse, but you cannot use it to change the position of the mouse.
15. shiftkey
Description:
Check the status of the shift key.
Syntax:
Event. shiftkey
Possible values:
When the Shift key is pressed, the value is true; otherwise, the value is false. Read-only.
16. srcelement
Description:
Returns the element of the trigger event. Read-only. For examples, see the beginning of this article.
Syntax:
Event. srcelement
17. srcfilter
Description:
Returns the filter that triggers the onfilterchange event. Read-only.
Syntax:
Event. srcfilter
18. toelement
Description:
Detects the elements that the mouse enters when the onmouseover and onmouseout events occur. Reference: 7. fromelement
Syntax:
Event. toelement
Note:
This is a read-only attribute.
Example: The following code shows a dialog box that displays "Mouse arrived" when you move the mouse over the button"
Code <SCRIPT>
19. Type
Description:
Event name returned.
Syntax:
Event. Type
Note:
The name of an event without a prefix of "on" is returned. For example, the Type returned by the onclick event is click.
Read-only.
20. x
Description:
Returns the x-axis coordinates of the upper-level elements with the position attribute relative to the CSS attribute. If there is no upper-level element with the position attribute in the CSS attribute, the body element is used as the reference object by default.
Syntax:
Event. x
Note:
If the mouse moves out of the window after an event is triggered, the returned value is-1.
This is a read-only attribute. This means that you can only use it to get the current position of the mouse, but you cannot use it to change the position of the mouse.
21. Y
Description:
Returns the Y axis coordinate of the parent element with the position attribute relative to the CSS attribute. If there is no upper-level element with the position attribute in the CSS attribute, the body element is used as the reference object by default.
Syntax:
Event. Y
Note:
If the mouse moves out of the window after an event is triggered, the returned value is-1.
This is a read-only attribute. This means that you can only use it to get the current position of the mouse, but you cannot use it to change the position of the mouse.
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