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I'm a very experienced programmer but I try to avoid Javascript because any description of how it works includes passages like this one from TFA: "This is beca

I'm a very experienced programmer but I try to avoid Javascript because any description of how it works includes passages like this one from TFA: "This is because a property declared in Rect.prototype is not available in Rect itself but only in objects created with new Rect. In this sense, Rect.prototype serves as a kind of “template” for objects produced by new Rect. As you can see, we are dealing with two different but quite similar concepts." Ohhhh...Kaaaaay. One tip I've learned when I have to use Javascript: Avoid 'this' whenever possible. There are 14 things 'this' can mean in Javascript, and whichever one it does mean depends on both the static context and the dynamic context (and possibly the phase of the moon). In most cases it's possible to avoid using 'this' by adding explicit variables. But I'm not sure it's always possible to avoid it. Yikes. Oh, and I'm never quite sure when it's a good idea to use 'new'. TFA addresses 'new' a little bit. At least it's not as big a can of worms as 'this'.

deleted 4y ago
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nicoburns 4y ago
> This is because a property declared in Rect.prototype is not available in Rect itself but only in objects created with new Rect. This isn't really any different to other languages. The equivalent for Java would be "(non-static) properties are not available directly on the class but only on instances of that class" > One tip I've learned when I have to use Javascript: Avoid 'this' whenever possible. Arrow functions help a lot with this. Their 'this' cannot be overriden and thus is determined by static context only. With regular functions, the rule is that it depends how their called: - If you call "foo.bar()" then "this" will be "foo". - But if you do "var baz = foo.bar" then call "baz()", then "this" will be undefined. - You can always set "this" explicitly by call a function with `.call`. In either "foo.bar.call(quz)" or "baz.call(qux)", "this" will be "qux". > Oh, and I'm never quite sure when it's a good idea to use 'new'. TFA addresses 'new' a little bit. At least it's not as big a can of worms as 'this'. Use "new" if and only if you're instantiating a class (whether that's written with the new class syntax or the older prototype syntax). That's it. It's possible to make a constructor work without "new", but it's an extra line of code and is generally considered non-idiomatic.

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nicoburns 4y ago

> This is because a property declared in Rect.prototype is not available in Rect itself but only in objects created with new Rect. This isn't really any different to other languages. The equivalent for Java would be "(non-static) properties are not available directly on the class but only on instances of that class" > One tip I've learned when I have to use Javascript: Avoid 'this' whenever possible. Arrow functions help a lot with this. Their 'this' cannot be overriden and thus is determined by static context only. With regular functions, the rule is that it depends how their called: - If you call "foo.bar()" then "this" will be "foo". - But if you do "var baz = foo.bar" then call "baz()", then "this" will be undefined. - You can always set "this" explicitly by call a function with `.call`. In either "foo.bar.call(quz)" or "baz.call(qux)", "this" will be "qux". > Oh, and I'm never quite sure when it's a good idea to use 'new'. TFA addresses 'new' a little bit. At least it's not as big a can of worms as 'this'. Use "new" if and only if you're instantiating a class (whether that's written with the new class syntax or the older prototype syntax). That's it. It's possible to make a constructor work without "new", but it's an extra line of code and is generally considered non-idiomatic.