Explains what libraries are and how they can be used to organized the shared code of your app.

Libraries are basically Javascript files where you can put code that is shared by different parts of your app. For example you have a library to encode and decode strings that you use in different actions of your app. Instead of repeating those algorithms in each action you can put them in a library and call it from the actions.

A library’s code looks like this:

var privateFunction = function(msg) {
  return '['+msg+']';

exports.logSomething = function(msg) {
  sys.logs.info('*** logged from library: '+privateFunction(msg));

The key is the exports variable. Everything that you want to expose from the library should be put in this object. Otherwise it won’t be accessible, like the function privateFunction in the above example.

The library will be accessible on any script using the namespace app.<libraryName>. For example if the library of the example above is called utils then you should be able to use the library like this on any script of the app:

var msg = record.field('description').val();

If you try to call app.utils.privateFunction(msg) an error will be thrown because that method was not exposed using the exports variable.

In the exports variable you can put whatever you want, it doesn’t have to be a function. You could expose constants like this:

exports.MAX_ORDERS = 100;
exports.MAX_AMOUNT = 50000;
Back to top