Asynchronous function call in Javascript

Question

My problem is this .I am new to javascript. I have a function which makes an asynchronous call to a Google map API (which returns location based on latlng) .This function in my code is MarkerCreaterPlusLocation. This call returns a value which I need in another function which is named MarkerCreater in my code. But the problem is that MarkerCreater does not stop for the MarkerCreaterPlusLocation to return the value .

To overcome this problem I tried using the callback for the MarkerCreater to get executed when the asynchronous function returns the value

The structure is as follows :

google.maps.event.addListener(map, 'click',addLatLng); //This code attaches the function to Listener



function addLatLng(event) {
        path = poly.getPath();
        path.push(event.latLng);
        MarkerCreaterPlusLocation(event.latLng,MarkerCreater);//MarkerCreater is the callback function
}




function MarkerCreaterPlusLocation(input,callback){
    location="l";
    geocoder.geocode({'latLng': input}, function(results, status) {
    if (status == google.maps.GeocoderStatus.OK) {
      if (results[1]) {
        location=results[1].formatted_address;
        callback(location,input);//I call the callback function upon the success of the result or otherwise
      } else {
        location="l"; 
        callback(location,input);
      }
    } else {
      location="l";
      callback(location,input);
    }
    });
}




function MarkerCreater(l,x){

    var marker = new google.maps.Marker({
        position: x,
        title: '#' + path.getLength()+l,
        icon: 'images/beachflag.png',
        map: map
});
    ///Some more javascript code 
}

I guess I am making mistake here as this does not seem to work . Rather it gives a 404 error which makes it still more difficult for me to understand it . Please help

You have a syntax error ... but maybe it's just a copy/paste issue. There is an additional "s" after location="l" in MarkerCreaterPlusLocation() — devnull69
– devnull69, Commented Nov 6, 2013 at 14:35
Thanks for pointing the error . I have corrected it . Yeah it was a copy paste error — penguinRaider
– penguinRaider, Commented Nov 6, 2013 at 14:37

Josh Harrison · Accepted Answer · 2013-11-06 14:43:29Z

3

Your location variable is not declared with var, which means it's in the global scope (i.e. window). So, setting location is actually setting window.location, which is causing the redirect to a 404.

To fix this, change the first line of your MarkerCreaterPlusLocation function to:

var location="l";

This will create it in the scope of the function only, and not the window.

answered Nov 6, 2013 at 14:43

Josh Harrison

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4 Comments

penguinRaider Over a year ago

Thanks !! s was copy-paste error . The error was with the declaration of location variable .

Josh Harrison Over a year ago

Great. Always a good idea to declare your variables with var to avoid problems like this, unless you really want to create a global variable.

geocodezip Over a year ago

FYI - That doesn't seem to work in Chrome. Better not to use "location" as a variable.

Josh Harrison Over a year ago

Works in latest Chrome/Mac for me, when the var declaration is inside a function. But you're right, better to not use it at all!

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