Many people don't understand it deeply, or they just follow others' opinions and easily understand it as going from angular1 to angular2. They think that if I change the version number, I won't recognize it at all. Now it has been upgraded to 4, which is easy for me.
In fact, we should first distinguish between angularjs and angular. These are two frameworks in terms of design ideas and underlying implementation. So when you upgrade from angularjs to angular, it is bound to be a disruptive change.
For the angular series, the change from 2 to 4 is just a change in version number, and most of them are compatible. Of course, due to the update of the typescript version and the upgrade of the main version number, you may upgrade angular to 4 or later , will bring some errors, but generally speaking, there will be no problems if the code is written according to the specifications.
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I maintain an angular template project on github, packaged with webpack, and contains most of the angular features. It was also based on 2.x before, and then 4.x came out, so I upgraded. The process was basically painless.
If you are interested, you can use it as a reference: https://github.com/ntesmail/a...