Javascript variables in an object

Question

I need to pass an object to another function but i have problems with global variables being referenced inside the object.

var a = 'first variable'; //SAMPLE GLOBAL VARIABLE
var b = 'second variable'; //SAMPLE GLOBAL VARIABLE

function iterator(options){
   for(var c in options){
    alert(c + ' ' + options[c]);    
   }
}

function main(){
   iterator({
      a:'5',
      b:'6'
   });
}

The functions should alert the output below

first variable 5
second variable 6

But instead I'm getting

a 5
b 6

I need to use variables inside the object.

Don't use local variable the same name as the global's it looks like you looking for troubles, there are tons of variables names that you can use. — lastboy, Jan 13 '14 at 07:05
possible duplicate of [Javascript: creating object with dynamic keys](http://stackoverflow.com/questions/19837916/javascript-creating-object-with-dynamic-keys) — Felix Kling, Jan 13 '14 at 07:35

score 2 · Answer 1 · answered Jan 13 '14 at 07:01

2

The a in the function is the local variable declared in the for loop.

var a = 'first variable'; //SAMPLE GLOBAL VARIABLE
var b = 'second variable'; //SAMPLE GLOBAL VARIABLE
var opts = {a: a, b: b};

function iterator(options){
   for(var a in options){
    alert(opts.a + ' ' + options[a]);    
   }
}

answered Jan 13 '14 at 07:01

xdazz

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sorry but the global variable opts cannot be global because i would be passing the object to a javascript library. Sorry if i did not mention i thought it wasn't a factor. – Kiel Jan 13 '14 at 07:07
Didn't work sorry. The two functions are actually separated to 2 javascript files. There will be lots of changes in the code to access the global variable opts from the other javascript file. But if I only have 1 file this works. – Kiel Jan 13 '14 at 07:13
@ling.s sorry just look at my comment to your answer and thank you – Kiel Jan 13 '14 at 07:23

score 2 · Accepted Answer · answered Jan 13 '14 at 07:02

2

As per your line I need to use variables inside the object, I suggest you rewrite your main as below:

function main(){
   var obj = {}
   obj[a] = '5';
   obj[b] = '6';   
   iterator(obj);
}

Since, a inside for-in loop will create new variable inside loop and refer to each key of object

answered Jan 13 '14 at 07:02

Dhanu Gurung

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This one works thank you. I might need to change alot of codes lol – Kiel Jan 13 '14 at 07:21
Also for the question above here is the answer for the single js http://jsfiddle.net/nB5m3/2/ from @ling.s – Kiel Jan 13 '14 at 07:29
@Kiel: This stackoverflow wouldn't be raised if you would have used different variable name inside for-in loop :). Since, you would have got what you wanted there itself. :) Anyway, Cheers!!! – Dhanu Gurung Jan 13 '14 at 07:33

score 1 · Answer 3 · edited Jan 13 '14 at 07:25

1

The a & b which you trying to access are tied to the Window object.

When you were printing 'a' or 'b' otherwise, it was printing the key 'a' from the Key/Value of you JSON.

$(window).load(function() {
main();
});

and,

function iterator(options){
   for(var a in options){
    alert(window[a] + ' ' + options[a]);    
   }
}

Fiddle

edited Jan 13 '14 at 07:25

Linga

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answered Jan 13 '14 at 07:07

gauravmuk

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`window[a]` is undefined – Linga Jan 13 '14 at 07:08
have you defined var a = 'first variable'; like the example? this should work, i have tested myself. – gauravmuk Jan 13 '14 at 07:10
and do this after window has loaded otherwise the variable might be undefined before the script actually executed. – gauravmuk Jan 13 '14 at 07:12
you are using `$(window).load(function() { main(); });`, but you didn't mention this in your answer. Also you can link the fiddle in your answer – Linga Jan 13 '14 at 07:24

score 1 · Answer 4 · answered Jan 13 '14 at 07:11

1

According to the edit, the OP now changed the variable name, so now variable a can be directly accessed

function iterator(options){
 for(var c in options){
     alert(a + ' ' + options[c]);    
 }
}

Here is the Fiddle

answered Jan 13 '14 at 07:11

Linga

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this works with one js file. I need the main function in a separate file that is why i cannot access the global variable a. I just made the js here simplier but the js file where the `function iterator` is present is actually inside a js library that i would access from the main javascript. – Kiel Jan 13 '14 at 07:17
thanks and sorry if i didn't mention the js library. – Kiel Jan 13 '14 at 07:22

score 0 · Answer 5 · answered Jan 13 '14 at 07:00

The var a here is specifically for creating a new variable with function scope that shadows the global variable:

function iterator(options){
   for(var a in options){
    alert(a + ' ' + options[a]);    
   }
}

You can't do that, if you still want to access the global...

Javascript variables in an object

5 Answers5