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Old July 19th, 2003, 01:24 PM
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Default Adding prototype functions

This is hard to word, so bear with me. I want to know if it is possible to add a prototype function that will directly modify the calling variable's value. Confused? Here is an example

<SCRIPT language="JavaScript">
String.prototype.trim = trim;

function trim()
{
    // Code that trims the white space from the calling myVar variable here
    // The value of myVar is retrieved from "this"
    // Modifying "this" causes an error. I think it this is because "this" is a reference to the current context object and not the actual calling variable
}
var myVar = ' name ';
myVar.trim();
alert(myVar);
</SCRIPT>

Can anyone tell me if this is possible? Thanks.
 
Old July 20th, 2003, 09:41 AM
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Default

I doubt it, JavaScript doesn't support pass by reference out parameters. When you call myVar.trim() you are in fact calling trim(myVar) and the function trim is written as:
Code:
function trim(this)
{
  //code here
}
i.e. the first parameter is the instance of the class that called the function.


--

Joe




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