Is it worth learning Angular 4 from scratch as an "investment" for 2018-2020?
You’re going to need to provide us with more back story than this. What language are you quitting?
Afterward, you have to explain what you are hoping to reap from your investment. If you want job opportunities, then Angular is a great investment because thousands of large companies are switching from their AngularJS installations to new, Angular versions. So if you want opportunities at major corporations, then Angular is an excellent choice.
If you want opportunities at smaller tech companies, then it is probably not your best choice. React has better traction with small organizations. The exception to that rule, though, are agencies. They love very heavy frameworks that provide tons of features and tools to rapidly do common tasks. That is why Ember is very successful in agencies but less so in other types of companies. The downside of agency work is that, while it’s always exciting, the pay is usually much lower than other companies. Ultimate point being, agencies will like Angular.
As to your last question, there is no chance that Google will be dropping support for Angular. Having their finger in that pot is WAY too important to them. Angular is their way of affecting the direction of web development, and that is critical. Chrome, Angular, Polymer: they are all part of the same overarching goal.
And while on the subject, Polymer is an excellent example of Google’s dedication. Polymer is dead. WebComponents are dead. Polymer is barely a blip on Google Trends. No one is talking about it on Reddit. Polymer was downloaded 1,423 times in the past month on NPM. React is downloaded that many times per 10 minutes. And yet, Google continues to push Polymer. Because, again, it is part of a critical element of Google’s long-term business goals: control and influence over the direction of the Internet.
就这个话题来说，Polymer是Google出品的一个绝佳案例。Polymer死了。WebComponents 也死了。在Google Trends的雷达上面，就只剩下一个闪烁的小点点了。Reddit上面再也没有人讨论它了。NPM上面，Polymer每个月的下载次数是1423，而React每10分钟的下载量就能达到这个数。 然后，Google还在持续推Polymer，同样因为Polymer是Google长期商业战略的核心要素：控制并影响互联网的演进方向。