For
example, a non-prototype JavaScript obtains a form field value as follows.
var field1=document.getElementById(???field1???).value;
The $F() function reduces the code to retrieve the form filed value as
shown below.
var field1=$F('field1');
3.2.3 $A() function
The $A()function is used to create an Array object from a node list or an
enumerable list. For example, an Array object may be created from a node
list object and the Array object navigated to retrieve node values. In the
following listing the HTML value of the first journal node in an XML
document is retrieved with the $A() function.
var nodeList=xmlMessage.getElementsByTagName
(???journal???);
var journalValue=$A(nodeList).first().innerHTML;
3.2.4 $H() function
The $H()function converts enumerations into enumerable Hash objects.
For example, variable journal is an enumeration of journals.
var journal={first: Oracle Magazine, second: ONJava,
third: AJAX Magazine};
The enumeration may be transformed into a hash with the $H()
function.
var journals=$H(journal);
3.2.5 $R() function
The $R()function is used to represent an ObjectRange object. For
example, the following ObjectRange object may be represented with
the $H() function.
ObjectRange range=new ObjectRange(10, 25, false);
The corresponding $R() function representation is as follows.
var range=$R(10, 25, false);
3.2 Overview of Prototype 47
3.2.6 $w() Function
The $w()function creates an array from a string using the whitepaces in
the string as delimiters.
Pages:
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62