In this part of the guide well construct the main program file of the weather application. To write and run all the code examples yourself, you need an editor to write code in, Terminal and GNOME 3 or higher installed into your computer. In this part we we'll go through the following parts:
Script for running the application
Libraries to import
Creating the main window for the application
Adding a grid and all the necessary widgets to it
Requesting the weather information asynchronously
Connecting signals to button and entry.
weatherapp.js
This line tells how to run the script. It needs to be the first line of the code and it needs to be executable. To get the execution rights go to Terminal and run in right folder: chmod +x scriptname. Or you can use the graphical filemanager. Just go to the right folder where your code is, right click you code file, choose properties, click the permissions tab and check the box for allow executing file as a program
In order to have a working program we need to import a GObject Introspection -library to our use. For working UI, we need Gtk. Gtk is imported in the beginning so we have it in our use everywhere. We also import our own local JavaScript library geonames to our use here.
In this section we create the grid we are going to use for positioning the widgets. All the buttons, labels and entries are initialized and placed on the grid. As seen from the placing of the different widgets, they don't need to be related only to one widget. At this point some of the labels don't have any content. The content for those widgets is applied later. If you run the application at this stage, you have the UI ready, but the widgets are not connected to anything. For this we need to first build the weather searching local library, and then get the information we need asynchronously. When we have our local library ready we can connect it to the necessary widgets.
This function is dedicated for calling for the weather information and updating labels and icons accordingly. In the beginning of the function we get the user input for the search. So here for the first time we use our own library and assign it to variable GeoNames. While assigning WeatherService we give it the station. The firs thing we do with GeoNames is to request weather. Everything after GeoNames.getWeather(function(error, weather) happens only if we either get an error message or weather information. If either doesn't come, the rest of the program works as normal, so main_Quit works.
Weatherapp.js file looks like this:
Running until you have all the autotools files ready. :
Use this command on terminal while developing your modules. When calling your program in this manner it knows where to find your custom JSlibraries, in this case geonames.js.