Injection Beyond Classes

So far providers have been used with Angular's @NgModule meta in anarray. providers have also all been class identifiers. Angular letsprogrammers specify providers with a more verbose "recipe". This is done withby providing Angular an Object literal ({}):

This example is yet another example that provides a class, but it does so withAngular's longer format.

This long format is really handy. If the programmer wanted to switch outChatWidget implementations, for example to allow for a , they coulddo this easily:

The injector can use more than classes though. useValue and useFactory aretwo other examples of provider "recipes" that Angular can use. For example:

In the hypothetical app component, 'Random' could be injected like:

The above example uses Angular's recipe. When Angular is toldto provide things using useFactory, Angular expects the provided value to bea function. Sometimes functions and classes are even more than what's needed.Angular has a "recipe" called useValue for these cases that works almostexactly the same:

View Example

In this case, the product of Math.random is assigned to the useValueproperty passed to the provider.