[benched]

Now, hold on there. These "anyone who" statements chafe me; like the junior dev who exclaimed "anyone who doesn't write unit tests shouldn't call themselves an engineer" in a meeting filled with people 15 years his senior who had collectively shipped far, far more successful software than him, without writing tests.

Several years ago, I led two different front-end web teams at a large, well-known company. I wrote a lot of JavaScript then. In fact, I wrote the core JS framework for one of the apps. I probably understood "this" at that time. I couldn't begin to tell you now, because I've been working on hit iOS games since - probably without knowing a lot of the nuances of Obj-C at times! There was no disaster back then - we shipped high-quality sites on time. There would be no disaster now, because if I went back to JS I'd crack a book.

The most important skills I bring to any project are a lot higher-level than the details of a particular language. I haven't made my career on one language or platform, but dozens of them. For the details, I work with reference material handy. After a month, I probably have a good grasp of whatever I'm working with. A year after that project, I probably don't, but I could bring it back easily.

[badman_ting]

That's cool. But don't write JS if you don't know what this does, because it will bite you.

[Bahamut]

Or just avoid using `this` unless you're sure about what it does in a particular context.

[gravity13]

Or just learn what 'this' means because, seriously, you're a programmer and it's not that hard to figure out.

[debaserab2]

That means that every person who reads your code also must understand "this" correctly in order to interpret your code correctly.

In certain team environments, I avoid 'this' because the programmer who is looking at this file next may not understand it's proper usage.

[svachalek]

Come on, there are what, half a dozen keywords in JavaScript? It's not that complicated.

[lomnakkus]

It's only upon reflecting upon "this" recently that I realized that it is (effectively) a global (thread-local) variable set by the X.Y() syntax. (I mean, I understood to be the case, but I just didn't realize the impliciations for understanding "this".)

The ECMAScript committe are taking steps to make "this" more useful, but the current semantic is so insane that I don't it's particularly surprising that people who aren't language lawyers don't understand it.

(*) Given that Javascript uses a single-threaded model.