If you write or type anything that is going to be shared with an audience, you must remember to read over it (or have a trusted acquaintance read over it for you). This goes not only for content, but code as well. The content bit makes sense. Pointless typos can just make you look silly, or even worse, careless. Not proofreading your code can have the same effect.
I studied computer programming for a couple of years right around the end of high school, beginning of college, and most of my teachers and professors wouldn’t allow us to even start typing our code until we had read over our code and corrected any glaringly obvious errors. For a long time after I started working with HTML, I forced myself back into this habit of reading over everything before posting it because I was notorious for either mistyping closing tags, or just forgetting them all together.
The results were usually somewhere between humorous and disastrous.
Back in April, I shared my sneaky trick for proofreading part of my code, but it does require a bit of diligence and willingness to take that extra time and go that extra mile to make sure your code won’t create more problems than it’s supposed to be solving.
If you are typing, always, always, always go back and read it over. Read it backwards if you have to, but read for errors!