Passing object in javascript function

Question

Say I already have many objects, like obj1, obj2, .....obj30.....

Now I am trying to write a function like this:

function blar(N){
 do something to objN
} 
blar('4');

So far it seems that the only way to do it is

function blar(thisObj){
 do something to thisObj
}
blar(obj4);

I wonder what is the right way to pass the N such that the function can use that N value to process objN.

Hope I make myself clear.

PS: I even try something like blar(obj+N) but apparently it's wrong too, as the system tries to find obj, which doesn't exist.

Object... Number. Let me try that again: Object, Number...

Jhourlad Estrella
– Jhourlad Estrella

2011-06-07 06:36:55 +00:00
Commented Jun 7, 2011 at 6:36 — Jhourlad Estrella
– Jhourlad Estrella, Commented Jun 7, 2011 at 6:36

Quentin · Accepted Answer · 2011-06-07 06:36:20Z

2

Use square bracket notation.

window['obj' + N];

This depends on them dangling off the window object and not being nicely scoped though.

… but if you have a bunch of objects, which are identified by being the same except for a number, then you should probably be storing them in an array in the first place. Then you would just:

myArray[N];

answered Jun 7, 2011 at 6:36

Quentin

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1 Comment

Vern Over a year ago

Oh, why I never think of array. Thanks for the great tip!

Jim Deville · Accepted Answer · 2011-06-07 06:37:46Z

0

Use eval:

function blar(N) {
    var obj = eval("obj"+N);
}

Or, if you can put those objects into an object, you can use []

function blar(N) {
    var obj = tracker["obj" + N];
}

answered Jun 7, 2011 at 6:37

Jim Deville

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Comments

Roland Illig · Accepted Answer · 2011-06-07 06:45:26Z

0

It's pretty simple:

function blar(objectNo) {
  var obj = eval('obj' + objectNo);
  alert(obj);
}

To give you some keywords for talking with others about this: what you want to do is to access an object by its name, in the current scope.

But note that the following doesn't work:

function main() {
  var a = 1, b = 2, c = 3;

  blar('a'); // doesn't work
  doSomething(eval('a')); // works
}

This is because the variable a is only visible in the main function, but not in blar. That is, the eval must be called in a scope where the variable is visible.

edited Jun 7, 2011 at 6:45

answered Jun 7, 2011 at 6:38

Roland Illig

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