In What Situations Would You 'Pass By Value' And 'Pass By Reference'

Nov 20, 2007

I have been trying to grasp the whole 'Pass By Value/Reference' thing for a few hours now. From what i can make out:

Passing by value will make a copy of the value, pass it as a function argument and the function will store the changes, the original value is not affected. So for example:

JavaScript Code:
var cost = 145;var postage = .3;var a = function() {return cost + postage;} //Using an Anonymous function for this

If you was then to pass the value of 'a' to a function argument it would copy and not change the original value.

If you pass by reference it will change the original value. When you pass a reference to a value through a series of different functions and the value is constantly being changed the change happens on the original value and can be seen outside the function.

The problem is i cannot think of how or why this would be used. I havn't got to develop many large applications so im trying to think of a few situations when passing by reference would be used.

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How To Pass This Type Of Reference Into An Array?

Oct 7, 2004

I am doing in a loop

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I need this several times in my script and I am sure it createst quite a lot of overhead. And I would like to pass xGetElementById(obj.ID+i) into an element array. like:

element = new Array();

So I can call back element[i] etc in my script by saving some overhead BUT (there is always a 'but' in my posts ) then:

position = element[i]

does not give anything.

Any clue? Is it possible?

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Sep 6, 2006

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I am not very experienced and have been piecing this together from
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To simplify all of this:

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heres the code, I've set i and j to 0 after the loop to highlight the issue.


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