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Usefulness should be your primary criteria.
Let’s unpack that a bit.
Software is a tool. We use it to build things of value for people. Either our customers, our users, or ourselves. We build to provide valuable software for people. A lot of developers lose sight of this when they look into new technologies. They fall in love with a technology because it’s shiny, or interesting, or scratches an intellectual itch. It’s the old “golden hammer” antipattern. Find something shiny and use it to build everything, even if it’s not the best tool for the job or doesn’t really improve upon existing technologies. We can do better. By focusing on what’s useful, we can skip the majority of new technologies and keep our sanity.
To figure out what’s useful, we need to ask a few questions. Write down your own answers as you read through this exercise.
Who is your audience?
As developers, we serve one or more audiences. Each of these audiences has different needs. It's your job to figure out which audiences you serve (or want to serve) and what they need. Perhaps you are spending most of your time in a full-time job, but want to start your own business. Perhaps you just work for the man. Figure out which audiences you serve and their relative priority. If you want to serve a new audience, think about what you will need to learn for them as well. Additionally, look for synergies. If you have more than one audience, find overlapping technologies.For example, if you want to build your own business on the side, use a similar tech stack to the one you use at your job.
Here’s a few audiences you can serve:
Your employer usually works with a specific tech stack in a certain industry. Focus your efforts on their current tech stack, new versions of that stack, and new technologies that would fit well within their current environment. If you work at a .NET shop, don't waste your time on Java. If you work on a native iOS or Android team, learning Ionic is a bad plan. Find technologies that help business units create more value. If you don't know how your business operates, add that to your "to learn" list.
Public Code / OSS
A good example of a useful technology would be Docker. Docker allows for faster and more consistent deployments, which helps improve time to market. This can give a business a real competitive advantage. Another good example would be mastering performance tuning in your particular stack. Lot's of case studies show performance adds to the bottom line.
Open source projects have different goals than enterprise shops. There’s some overlap, but OSS is built differently. If you do OSS, figure out which projects you want to contribute to and focus on their tech stacks. Also think about what value you can bring to the developer community.
If you run an app business or an ISV (independent software vendor), focus on technologies that create customer value. For example, while functional programming is cool, you’re better off mastering digital marketing or product design instead. Focus on technologies that help you get products in front of customers quickly. This doesn’t always mean new technology. There are a lot of Rails 2, jQuery, and ASP.NET Webforms apps out there still generating significant value for their customers.
It’s OK to learn something just for fun. Lots of people write code as a hobby, but make sure you understand that the time you spend building robots or smartwatch apps is hobby time, not professional development time.
I have three audiences. I work on a team that builds data driven applications using .NET Core, Angular, TypeScript, and Spark. I also serve the broader technical community by speaking at conferences and blogging. Eventually, I want to build a small software product and sell it. I achieve synergy by focusing my community efforts on things that I either use in my day-to-day work (like Angular) or things that will serve me in business (innovation).
What makes you special?
What special qualities do you bring to the table? Are you an amazing debugger? Are you a UX genius? Are you good at cutting to the core of team issues? Do you have an underrepresented perspective? Everyone has specific skills that are both unusual and valuable. Focus your development efforts on expanding and complementing what makes you special. For example, if you're a talented at building user interfaces, spend the time to skill up on Angular or React. If you're the performance expert, check out that shiny new profiling tool. It's often better to expand a strength than moderate a weakness.
I know more about UX and front end development than most of the .NET developers I work with. I'm also good at keeping my cool when things get crazy. People have called me "Spock" before, which I take as a compliment. I also have a variety of non-developer skills, like public speaking and psychology, that allow me to think differently.
What do you already know?
My current skill set revolves around Angular, TypeScript, SQL Server, and ASP.NET MVC. I want to learn more about data tools, especially the ones in Visual Studio. The Microsoft ecosystem is gaining some interesting data capabilities that can add a lot of value. I may also do an exploration of Ionic 2 and progressive web applications. Both of those are good ways to use existing skills in a new way. I'm also working on my public speaking and written communication. Communications skills never become obsolete.
Now that you know what's useful for your situation, let's use that knowledge to make your life easier. You likely have a list of technologies that you're interested in or feel obligated to keep up with. I have a whole radar of them. Take that list and run it through the criteria you figured out. If the technology doesn't help you add value to one of your audiences, cross it off the list. Rank everything else based on its relative value. Use your criteria to combat "shiny object" syndrome when you encounter a new technology. You'll likely still have more things on your list than you can learn, but your list should be manageable.
If you want to survive the constant stream of new technologies with your sanity intact, make your primary technology criteria value.