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Finding your way around
The JavaScript Object hierarchy is a structured set of programmable
elements that Web pages are made up of. By learning this structure, you
can use JavaScript to control the appearance and behavior of elements on
your Web pages.
Try to understand the code and predict what will happen when you push
the different buttons. This little example will serve as an indicator of
your understanding of JavaScript up to this point.
<SCRIPT>
function writeField()
{
var fld = "Yo, what's up!";
document.forms[1].elements[0].value = fld;
}
function returnValue(expression)
{
var fld = expression;
return fld;
}
function changeBtn(btn)
{
if (btn.value == 'Push Me') btn.value
= 'PUSH ME';
else btn.value = 'Push Me';'
}
</SCRIPT>
<FORM>
<INPUT
TYPE="text"
VALUE="bla bla bla">
<INPUT
TYPE="button"
VALUE="Write"
onClick="document.forms[1].Name.value='Yo!';">
<INPUT
TYPE="button"
VALUE="writeField"
onClick="writeField();">
<INPUT
TYPE="button"
VALUE="returnValue"
onClick="document.myForm.elements[1].value=
returnValue('frank@sislands.com');">
</FORM>
<FORM NAME="myForm">
Name: <INPUT
TYPE="text"
NAME="Name"
VALUE>
E-Mail: <INPUT
TYPE="text"
VALUE>
<INPUT
TYPE="button"
VALUE="Push Me"
onClick="changeBtn(this);">
</FORM> |
