Set a new variable using variables inside a function

Question

I am creating a web app using geolocation. So far I have it set up and working so when the user visits they are prompted to allow location services, then are presented with an alert (Not permanent, just for testing purposes.)

I am using this:

navigator.geolocation.getCurrentPosition(foundLocation, noLocation, {enableHighAccuracy:true});

function foundLocation(position)
{
    var lat = position.coords.latitude;
    var long = position.coords.longitude;
    alert('We know you are here '+ lat +','+ long);
}
function noLocation()
{
    alert('Could not find location');
}

Then I have a variable outside this called "address" which is the URL for the API call:

address = "http://api.wunderground.com/api/geolookup/hourly/conditions/astronomy/alerts/forecast/q/[LOCATION].json"

My question is how can I get the lat and long out of the function and insert them into the URL? I have tried a few methods, but they all return "undefined" so I am obviously doing something wrong.

Any help is greatly appreciated!

Thank you.

Community · Accepted Answer · 2017-05-23 12:12:14Z

2

You have to understand the scope of a javascript variable, please, read this post: What is the scope of variables in JavaScript?

var address = '';

function setLocation(position)
{
    var lat = position.coords.latitude;
    var long = position.coords.longitude;
    address = "http://api.wunderground.com/api/geolookup/hourly/conditions/astronomy/alerts/forecast/q/" + lat + "," + long + ".json";
}

Besides, there is a better approach to solve your problem. The easiest approach is to create a global object with a unique name, with your variables as properties of that object and methods to change the variables, like:

var geolocation = {};
geolocation.latitude = 0;
geolocation.longitude = 0;
geolocation.address = "";
geolocation.setLocation = function(position) {
    geolocation.latitude = position.coords.latitude;
    geolocation.longitude = position.coords.longitude;
    geolocation.address = "http://api.wunderground.com/api/geolookup/hourly/conditions/astronomy/alerts/forecast/q/" + geolocation.latitude + "," + geolocation.longitude + ".json";
};
geolocation.show = function() {
  alert(geolocation.latitude + " " geolocation.longitude + " " + geolocation.address);
};

And so on. Now, everywhere in your file if you use:

geolocation.setLocation(position);
geolocation.show();

It will show the new values from the global object.

UPDATE

Keep in mind that a variable or object in javascript will be global if there is no wrapper around it, like another function or object.

edited May 23, 2017 at 12:12

CommunityBot

11 silver badge

answered Sep 13, 2012 at 14:58

lolol

4,4203 gold badges39 silver badges55 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Clay_Cauley Over a year ago

This is excellent, and thank you for all your help and explanations. I'm still learning so I appreciate people like yourself that are willing to help.

lolol Over a year ago

Thank you! Don't forget to vote up the guy on the "javascript variable scope" post if it helps you! Good luck!

Richard Dalton · Accepted Answer · 2012-09-13 15:03:55Z

1

Can you not just update the address directly from the function like this?

navigator.geolocation.getCurrentPosition(foundLocation, noLocation, {enableHighAccuracy:true});
var address = "http://api.wunderground.com/api/geolookup/hourly/conditions/astronomy/alerts/forecast/q/[LOCATION].json"

function foundLocation(position)
{
    var lat = position.coords.latitude;
    var long = position.coords.longitude;
    alert('We know you are here '+ lat +','+ long);
    address = address.replace('[LOCATION]', lat + ',' + long);
}

edited Sep 13, 2012 at 15:03

answered Sep 13, 2012 at 14:56

Richard Dalton

35.8k6 gold badges75 silver badges92 bronze badges

Collectives™ on Stack Overflow

Set a new variable using variables inside a function

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related