Dear, readers! Today I have prepared an interesting topic about “What is dependency injection in AngularJS?” Now, I’ll be taking a closer look at dependency injection. Of course, you can learn how it can be working in AngularJS and the importance of understanding it in the beginning place.
In my opinion, let’s examine this in a little more detail.
What is Dependency Injection?
At this point, I want to introduce to you the general definition. Also, you can find a lot of variants of dependency injection out there. Dependency Injection is a model in which a class can get dependencies externally, rather than internally. According to AngularJS, you can exchange the word class with components and would expect an identical item. This model also supports a method named the Dependency Inversion Principle, a form related to decoupling software modules.
Three kinds of classes
Research has found this pattern involves 3 types of classes. Have you ever heard about these types? If so, it’s time to read about it. And now, I want to demonstrate to you these kinds.
- Guest class
Needless to say, this kind of class depends on the service class.
- Service class
To put it simply, this type of class presents service to the guest class.
- Injector class
I wanna tell you this class includes the service class object in the guest class.
To my mind, you’ve understood all these types. It seems to me, this point is exactly what you need. So, it’s time to move the next point.
Types of Dependency Injection
Maybe you have read of these types, if not, I will clarify the most important issues. I certainly hope this information will be useful for you. According to experts, they divided it into three ways. They are: through a constructor, through a quality, and a process. Let’s discuss in more detail.
Constructor Injection
You must admit that in this type the injector provides the service through the guest class constructor.
Quality Injection
According to this injection, it is clear from the facts that the injector provides the province with a public quality of the guest class.
Process Injection
Many studies have shown that in this type of injection, the guest class performs an interface that represents the method to provide the dependency, and the injector practices this interface to give the dependency to the guest class.
So, I truly hope I provided enough info to make a clear observation about types of Dependency Injection.
How does Dependency Injection work in AngularJS?
As everyone knows, AngularJS plays an important role in this process. It is often said that it’s useful to know the methods that the AngularJS can present in your code. Here is a shortlist of some methods:
Module methods
You will notice these methods which can define uses to run at call time. I can define functions to run at the form and run time for a module by calling the config and run methods. These functions are injectable with dependencies just like the company uses above.
Controllers
Many studies have shown that this method includes specific provinces such as ctrl and scope. Unlike services, there can be various examples of the same type of controller in an application. It is widely believed that controllers are connected with a component in the DOM and so are presented with a way to the scope.
Factory methods
It’s no secret that methods are expressed with modules. The method you define a directive, service, or filter is with a factory office. The industry methods are listed with modules.
So, now you’ve understood all the methods which can help work in AngularJS Development.
Why Dependency Injection?
I wanna say this part motivates and explains AngularJS’s use of DI. I hope that this introduction has interested and stimulated you. As usual, there are just three steps a component can get a hold of its dependencies. And now, let’s discuss them.
- The element can build reliance, generally using the original operator.
- The component can look up the dependency, by connecting to a global changeable.
- And the last, the element can have the dependency moved to it where it is required.
Unfortunately, the first and the second choices of producing or looking up dependencies are not optimal because of the difficult code and the dependency on the part. At the same time, this makes it difficult to change the addiction. As a result, this is particularly problematic in tests.
According to the third choice is more feasible because it takes away the functions of position of the dependency from the element. One benefit of this that the dependency is easily given to the element.
Conclusion
In conclusion, I want to say that this article was very useful for developers. I tried to demonstrate the most important points. You’ve read a piece of information about kinds of classes. Such as:
- Guest class
- Service class
- Injector class
Also, I presented to you, different types of Dependency Injection. Here are the lists of them:
- Constructor Injection
- Quality Injection
- Process Injection
Thank you for reading! I hope you found it interesting!