Several years ago I had a self-taught colleague who changed careers in his 40s from a very successful and highly skilled horn player in an orchestra to web developer. This came about after an injury to his hand meant he could no longer play very well.
Fortunately for some years before the injury he had self-taught himself PHP, DB and web development in order to create a system to help schedule orchestra members for gigs.
My impression of him was high, and I greatly admired his courage for making such a drastic change in his life. He came to us with some good skills a hunger to learn.
Of his strengths the one I remember the most was a level of maturity and thoroughness in the code developed. This is in contrast to the full-speed quickly hack something together to finish it as soon possible mentality I have seen a few times now in younger junior devs fresh out of uni.
Areas for improvement were mostly around code style, using GIT or other source control, other team processes and practices. There were no-doubt some areas of PHP and DB development that benefited from having peer reviews. Nothing too different than other junior developers in the team.
As for his confidence, he seemed fine (though I can imagine their must have been times of doubt and imposter syndrome). He was determined to make the best of his career switch, was positive, did some fantastic work for us.
Last I heard he is still going strong in the IT industry working for the company that took a chance and hired him as a junior developer.
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