How
It Works
In
the body of the page we define a button called myButton within a form called form1.
Within the attributes of the <INPUT> tag, we attach the function myButton_onmouseup()
to the onmouseup event handler, and the function myButton_onmousedown() to the
onmousedown event handler.
<FORM NAME=form1> <INPUT TYPE='button'
NAME='myButton' VALUE=' Mouse Goes Up ' onmouseup="myButton_onmouseup()"
onmousedown="myButton_onmousedown()"> </FORM>
|
The
myButton_onmouseup() and myButton_onmousedown() functions are defined in a script
block in the head of the page. Each function consists of just a single line of
code, in which we use the value property of the Button to change the text that
is displayed on the button's face.
An
important point to note is that events like onmouseup and onmousedown only trigger
when the mouse pointer is actually over the element in question. For example if
you click and keep held down the mouse button over our button, then move the mouse
away from the button before releasing the mouse button, you'll find that the event
does not fire and the text on the button's face does not change. In this instance
it would be the document object's onmouseup event handler code that would fire,
if we'd connected any code to it.
Don't
forget that, like all form element objects, the Button object also has the onfocus
and onblur events, though they are rarely used in the context of buttons.
The Submit
and Reset Buttons
Two
additional types of button are the submit and reset buttons. Defining the submit
and reset buttons is done in the same way as defining a standard button, except
that the TYPE attribue of the <INPUT> tag is set to submit or reset rather
than buttons. For example, the submit and reset buttons in the earlier screenshot
were created using:
| <INPUT TYPE="submit" VALUE="Submit"
NAME="submit1"> |
| <INPUT TYPE="reset" VALUE="Reset"
NAME="reset1"> |
These
buttons have special purposes, which are not related to script.
When
the submit button is clicked, the form data from the form that the button is inside
gets automatically sent to the server, without the need for any script.
When the reset
button is clicked, all the elements in a form are cleared and returned to their
default values; the values they had when the page was first loaded.
The
submit and reset buttons have corresponding objects called and , which have exactly
the same properties, methods, and events as a standard Button object.