Chapter 9. Programming Language Trends

At O’Reilly Media, we have a data mart containing six years of job posting data from, a job posting site that aggregates most of the online job postings in the US. Below, we take a look at job posting trends involving computer languages over the past three years. This data provides context for the Bluehost data.

You will notice that in each of these charts there is a light green area plotted behind the bars. Those green areas show the peaks and valleys of all job postings, not just technology jobs or postings for the specific language. This way you get a sense if the whole US economy is trending up or down and does the language mirror that trend.

Note that the scale of these charts is not the absolute number of job postings, but is normalized relative to the number in January 2009, which is set at 100. A value of 200 thus means that there has been a 100% increase in the number of postings since January 2009.


JavaScript seems to be a close proxy to what is happening in the overall market. There are few monthly instances where JavaScript is counter to the overall market. March 2009 is an easy anomaly to spot. Pay attention to the scale as the other languages are not quite as big, so the charts may look similar, but scale is important.

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The next chart is for Perl. There was a slowing in job postings starting in 2007 which is not ...

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