Global var in JavaScript

Question

This is annoying me.

I'm setting an array in beginning of the doc:

 var idPartner;

 var myar = new Array();
 myar[0] = "http://example.com/"+idPartner;

And I'm getting a number over the address, which is the id of partner. Great. But I'm trying to set it without success:

 $.address.change(function(event) {
   idPartner = 3;
   alert(idPartner);
 }

Ok. The alert is giving me the right number, but isn't setting it.

What's wrong?

Answer 1

Try this:

var myvar = ["http://site.com/"];


$.address.change(function(event) {
   myvar[1] = 3;
 }

then use myvar.join () where you need the full url.

Answer 2

The problem here is that at the line

myar[0] = "http://site.com/"+idPartner;

..you perform a string concatenation, meaning you copy the resulting string into the array at index position 0.

Hence, when later setting idPartnerit won't have any effect on the previously copied string. To avoid such effect you can either always construct the string again when the idPartnervariable updates or you create an object and you evaluate it when you need it like...

var MyObject = function(){
   this.idPartner = 0; //default value
};

MyObject.prototype.getUrl = function(){
   return "http://site.com/" + this.idPartner;
};

In this way you could use it like

var myGlblUrlObj = new MyObject();

$.address.change(function(event){
   myGlblUrlObj.idPartner = ... /setting it here
});

at some later point you can then always get the correct url using

myGlblUrlObj.getUrl();

Now obviously it depends on the complexity of your situation. Maybe the suggested array solution might work as well, although I prefer having it encapsulated somewhere in an object for better reusability.

Answer 3

myar[0] = "http://site.com/" + idPartner;

After this line, myar[0] = "http://site.com/undefined" and it has nothing to do with the variable idPartner no more.

So, after that changing the value of idPartner will affect the value of myar[0].

You need to change the value of myar[0] itself.