Rules for incremental upgrade to Angular

It will be easier to do an incremental upgrade if we adhere to the following set of rules:

• Implement one component per file; it helps to isolate the components and migrate them one by one.
• Apply modular programming and arrange the folder by features; this will enable the developers to concentrate on migrating one feature at a time.
• Use a module loader; following the preceding rules, you will end up with a large number of files in a project. This creates the hassle of organizing the files and referring them in the correct order in the HTML pages. When you use a module loader such as SystemJS, Webpack, or Browserify, it enables us to use TypeScript built-in module systems. This enables the developers to import or export features explicitly and share them between various parts of the application in the code.
• Install TypeScript first; it is good to bring in the TypeScript compiler before starting the actual upgrade process. This can be achieved by a simple step of installing the TypeScript compiler.
• Use Component Directives; it is good practice to use Component Directives rather than ng-controller and ng-include in the AngularJS apps so that in Angular, migrating the Component Directives will be much easier than migrating the controllers.