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Usage of reference parameters and how it can be used in functions - JavaScript

Posted on 2011-09-11
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Last Modified: 2012-06-22
Hi,

Can you please let me know with simple examples on:

Usage of reference parameters and how it can be used in functions - JavaScript

Thanks
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Question by:milani_lucie
2 Comments
 
LVL 40

Expert Comment

by:Gurvinder Pal Singh
ID: 36520708
like this

function a()
{
   alert("1");
}

//settimeout will use the function reference to call it

setTimeout(a, 1000); //a method will be called after a second
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LVL 17

Accepted Solution

by:
sonawanekiran earned 2000 total points
ID: 36520843
When passing in a primitive type variable like a string or a number, the value is passed in by value. This means that any changes to that variable while in the function are completely separate from anything that happens outside the function. Let’s take a look at the following example:
function myfunction(x)
{
      // x is equal to 4
      x = 5;
      // x is now equal to 5
}

var x = 4;
alert(x); // x is equal to 4
myfunction(x); 
alert(x); // x is still equal to 4

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Passing in an object, however, passes it in by reference. In this case, any property of that object is accessible within the function. Let’s take a look at another example:

function myobject()
{
	this.value = 5;
}
var o = new myobject();
alert(o.value); // o.value = 5
function objectchanger(fnc)
{
	fnc.value = 6;
}
objectchanger(o);
alert(o.value); // o.value is now equal to 6

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