book related questions here

jminatel · January 11th, 2006, 11:18 AM

Don't forget, this particular forum exists mainly to discuss the book Professional JavaScript for Web Developers. Fair game includes anything that you can't understand, think doesn't work right, or even "why does it work this way" related to something specific in the book. General "how do I do this with JavaScript" questions posted here might get answered but they might not. Your best bet for non-book JavaScript "how do I" questions however is in the "JavaScript How-To" forum here at:
http://p2p.wrox.com/javascript-how-87/

Thanks for your participation.

Jim Minatel
Senior Acquisitions Editor
Wiley Technology Publishing
WROX Press
Blog: http://wroxblog.typepad.com/
Jim's Book of the week: No book this week - Donate to the Red Cross!

dharrison2010 · January 30th, 2013, 07:52 PM

Confused...in the book page 88-89 you make reference to passing references is actually being passed by value; however, the code that is used to prove this does not make since to me. Inside the function setName(obj) you are creating a new Object reference, which in other languages would say this is a local variable and will die at the end of the function, thus not reflecting a change on the Object created outside the function. Here is a couple of examples:

HTML Code:

        var person = new Object();
	
	person.name = 'John';
	
	console.log(person.name);
	
	function changeName(obj){
		obj = new Object();
		obj.name = 'Nick';
		return obj.name;
	}
	
	console.log(changeName(person));
	console.log(person.name);

This example produces: John, Nick, John

HTML Code:

        var person = new Object();
	
	person.name = 'John Doe';
	
	console.log(person.name);
	
	function changeName(obj){
		// obj = new Object(); comment out
		obj.name = 'Nick';
		return obj.name;
	}
	
	console.log(changeName(person));
	console.log(person.name);

This example, commenting out the creation of a new Object inside the function, produces: John, Nick, Nick

Which suggest to me that it was in fact passed by reference and not by value.

Any further clarity on this would be appreciated.

Regards,

Darren