Pass parameter to callback function

Question

my code

// do ajax request and get JSON response

for (var i = 0; i < data.results.length; i++) {  
    result = data.results[i];
    // do stuff and create google maps marker    
    marker = new google.maps.Marker({  
        position: new google.maps.LatLng(result.lat, result.lng),   
        map: map,  
        id: result.id  
    });  
    google.maps.event.addListener(marker, 'click', function() {  
        createWindow(marker.id); //<==== this doesn't work because marker always points to the last results when this function is called
    });  

}

How to solve this?

Answer 1

The classic closure problem strikes again!

  google.maps.event.addListener(marker, 'click', function(id) {
    return function(){
      createWindow(id); //<==== this doesn't work because marker always points to the last results when this function is called
    }
  }(marker.id));

Answer 2

Looks like you've got a closure problem. See these questions:

• google maps api all markers opening the same infowindow
• google maps trouble closures passing by reference
• dynamically adding listeners to google maps markers

Answer 3

Try this:

with ({ mark: marker }) {
    google.maps.event.addListener(mark, 'click', function() {  
        createWindow(mark.id);
    });
}

An example that demonstrates the use of with:

for (var i = 0; i < 10; i++) {
    setTimeout(function() { console.log(i); }, 1000);
}

The above will log 10 ten times.

for (var i = 0; i < 10; i++) {
    with ({ foo: i }) {
        setTimeout(function() { console.log(foo); }, 1000);
    }
}

This will log 0 to 9, as desired, thanks to with introducing a new scope.

JavaScript 1.7 has a let statement that is nicer, but until that is widely supported, you can use with.

And use var for your variables.