Attaching parameters with javascript closures to default parameters in anonymous functions

Question

I want to add some extra parameters to the Google geocoder API call as I'm running it in a loop, but am not sure how to append closure parameters to their anonymous function that already has default parameters that are passed in by the call to the API.

For example:

for(var i = 0; i < 5; i++) {
     geocoder.geocode({'address': address}, function(results, status) {
         // Geocoder stuff here
     });
}

I want to be able to use the value of i in the passed geocoder.geocode() anonymous function, but if I had a closure using }(i)); on line 4 for example that would replace the first parameter which would break the geocoder.

Is there a way I can use closures, or pass the value of i into the anonymous function at all?

Effectively what I want to do is:

geocoder.geocode({'address': address}, function(results, status, i) {
    alert(i); // 0, 1, 2, 3, 4
}(i));

but working :-)

Answer 1

function geoOuter(i) {
    geocoder.geocode({'address': address}, function(results, status) {
         // Geocoder stuff here
         // This has access to i in the outer function, which will be bound to
         // a different value of i for each iteration of the loop
     });
}

for(var i = 0; i < 5; i++) {
    geoOuter(i);
}

Oughta do it...

Answer 2

You can access i directly from you anonymous function (via closure), but you need to capture it so that each call to geocode gets its own copy. As usual in javascript, adding another function will do the trick. I renamed the outer i variable to make it clearer:

for(var iter = 0; iter < 5; iter++) {
    (function(i) {
        geocoder.geocode({'address': address}, function(results, status) {
            // Geocoder stuff here
            // you can freely access i here
        });
    })(iter);
}