Question

Possible Duplicate:
How to pass values to a callback function at the time of the request call?

I know this is a general problem and not only in node.js. I have to pass a variable from the for loop to a function which I want to generate. The functions are stored in an array and have to remember these variables.

Here is my example:

for(var i = 0; i < administratorIds.length; i ++){
  adminCallbacks[adminCallbacks.length] = function(callback){
    model_user.getById(administratorIds[i], function(user){
      administrators[administrators.length] = {name: user.getName()};
      callback(null, null);
    });
  };
}

Answer 1

You need to create a new variable scope for each iteration of the loop.

Only way to do that will be by invoking a function.

for(var i = 0; i < administratorIds.length; i++){
  adminCallbacks[adminCallbacks.length] = createHandler(i); // pass i
}

 // receive i as j-----v
function createHandler(j) {
     // return a function...
    return function(callback){
          // ...that uses j-----------------v
        model_user.getById(administratorIds[j], function(user){
          administrators[administrators.length] = {name: user.getName()};
          callback(null, null);
        });
    };
}