This Object; Variable And Function Name Conflicts - Adobe ACROBAT FORMS JAVASCRIPT OBJECT Specification

this Object

In JavaScript the special keyword "this" refers to the current object. In Acrobat Forms the
current object is defined as follows:
• In an object method, it is the object to which the method belongs.
• In a constructor function, it is the object being constructed.
• In a function defined at the
that calling functions pass the document object to any function at this level that
needs it.
• In a Document level
therefore can be used to set or get document properties and functions.
For example, assume that the following function was defined at the Plug-in folder level:
function PrintPageNum(doc)
{ /* Print the current page number to the console. */
console.println("Page=" + doc.page);
}
The following script outputs the current page number to the console (twice) and then prints the
page:
PrintPageNum(this);
console.println("Page=" + this.pageNum); /* Same as the previous call. */
this.print(false, this.pageNum, this.pageNum); /* Prints the current page. */

Variable and Function Name Conflicts

Variables and functions that are defined in scripts are parented off of the this object. For
example:
var f = this.getField("Hello");
is equivalent to
this.f = this.getField("Hello");
with the exception that the variable "f" can be garbage collected at any time after the script is
run.
If a script uses a name that conflicts with a document level property or method and the this
object is the current document then a run-time error will result: Invalid or unknown property,
set not possible.
The following script fragment will generate such an error:
var pageNum = this.pageNum;
To avoid such an error, rename your variables and functions to avoid conflict:
var pNum = this.pageNum;
Acrobat Forms - JavaScript Object Specification
Plug-in folder level
script or Field level
/* Must pass the document object. */
it is undefined. It is recommended
script it is the document object and
52