Now in order to get "core-js" from GITHUB and get installed in our system for Angular 2 project, do follow as shown in the image down below. Open Start Menu > go to "Node.js command prompt" and type the command once command prompt is open
npm install core-js
Once installation is done it will be available under "node_modules" folder within Angular 2 project. Now "Shim.js" can be used into Angular 2 project.
If we define zone.js which is given on the GITHUB site where it is available as download over there it is written a simple line – "A Zone is an execution context that persists across async tasks".
Here is the link https://github.com/angular/zone.js/ for GITHUB with which you can download and import "zone.js" into your Angular 2 project.
Below image shows Angular 2 application which is executing both synchronous task called function "a1" and asynchronous task called function "a2" under zone.js.
The useful part is that the zones "persist across async tasks", so an asynchronous task "a2" will run within the same zone that it was created along with synchronous task "a1". Zones just not only allow us to run code in their own work space area but it also allow us to hook into them in order to detect when asynchronous tasks "a2" start or got finish.
"Reflect Metadata allows a user to create decorator or to add metadata or specify attribute for his project classes."
It is included in the Angular 2 project by doing installation that is done with the help of command which is written in the node.js command prompt
npm install reflect-metadata
After you complete the installation via node.js command prompt now it is readily available to use it in your Angular 2 project. Just import it under your project by mentioning "import" syntax and installation path where reflect-metadata file is available as shown in the image down below.
With this you can now decorate by applying decorator on the class level on if you wish add metadata on the method level. Down below we have specified it just above to Add()method.
This type of representation of decorator above method level is called as method level decorator.
Below is the image screenshot from "index.html" showing the portion for configuring "SystemJS". Here mainly we have to configure three things. First specify the config file as "systemjs.config.js" file it will let know "SystemJS" which files to be loaded in the browser. Secondly under the "import" specify the file name which will be invoked at the start. And at last within the place holder specify the selector which is put under the component. And then that HTML page of that component will be loaded.
Hope that you got a brief understanding on Angular 2 dependencies now go and view the following project series video which will more enhance your learning :