One of the best proxies for how hard it is for a skill to be filled is salary levels. This is because there are certain skills that are highly in demand but that demand is being filled. The example of React.
This is the wildly popular Javascript library created by Facebook which has seen a huge uptick in use. If you look at Hacker News’s hiring boards, you’ll find that it is the most sought-after technology right now, beating out Other popular Javascript libraries like AngularJS and Node.js.
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But has this popularity meant that React commands the highest salaries?
We did some research using PayScale and found that at the top end of the range for the US, a software Engineer who knew React could earn . Now that isn’t too bad but it doesn’t make it even onto the top 20 most valuable skills. Instead we found that the most sought after skill was MapReduce, earning a whopping .
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This was followed by Hive, Natural Language Processing, Machine Learning, and Solr. I would say that these are objectively the hardest to fill right now as if they were easier to fill like React, the salaries they would command would be lower.