Pre-defining a function that can pass variables.

aluminumpork · July 22nd, 2006, 02:51 AM

Now I'm not talking about:

function(var){
alert(var);
}

or like that.

I'm talking about create a function like:
var testFunction = Function('callMe();');

That's fine as well, but:

var testFunction = Functn('callMe(varToPass);');

will only pass the variable that is currently initialized. This make send to me, but what I'm looking to do is make a function (in a similar fashion I hope) that can pass a variable by the specified at a future time.

Say I'm setting up an object that I'm going to send to a function.

So,

var testObj;
testObj.callThisFunctionWhenDone = Function('callWhenDone(passThisVar)');
testObj.init();
testObj.start();

Now when the whole process is done, it is going to return some data and call the function created right here at the beginning. I want the data passed to the defined function. I know I may not be explaining this very clearlly, but hopefully somebody understands what I'm talking about. The function is for an xmlHttpRequest with async on, so I'm looking for a way for the endFunction (when the request is all done) to be able to use the xmlHttp object without using global vars.

Thanks a lot.
AluminumPork

spinal007 · July 22nd, 2006, 07:15 AM

Ok, we need to get this string:
... = Function('callWhenDone(passThisVar)');
do you mean...
... = function(){ callWhenDone(passThisVar); };
Were you just giving passing the idea or actually showing code???

***
You'll need to clarify that before I can help you. I don't know exactly what the situtation is but this might help... (based on what you've given me)

For a string, you could do this:
var testFunction = Function('callMe("'+varToPass+'");');

For a number, you could do this:
var testFunction = Function('callMe('+varToPass+');');

For a dom element, try passing the element id as a string.

***
Another approach would be to, instead of sending the variable as a parameter, send a function as a parameter which would get the current value of the variable you're trying to pass. eg:
... = Function('callWhenDone(LoadTheVarToPass())');

***
I know what the problem with the above is: the variable varToPass will have been updated by the time the function is called. Well, how you solve this will depend on your code's structure / variable scope.

If varToPass is a global variable, then this should work. As far as I now, it's the proper way to do it and it would always execute using the current value of varToPass.

// define function
obj.testFunction = new function(){ callMe(varToPass); };
// call function
obj.testFunction();

***
hope that helps...

aluminumpork · July 22nd, 2006, 03:07 PM

Wow, what a great reply. Yes I was referring to Function('');
Sorry for not clarifying that. But reading through your reply I realized I could
just do var functionToCall = function(varToPass){ realFunctionToCall(varToPass); }

This I can call it like functionToCall(varToPass) and everything gets passed through. Works great and I no longer have to use any global vars, YAY!

Thanks so much for your help!

spinal007 · July 24th, 2006, 08:16 AM

No worries. It was a good exercise going through the options...
It would ebe great if you could stick around and be part of the forums.
It's very sad when people get help and leave! LOL