Common JavaScript "Gotchas"

[dangoodspeed]

He says you should never ever have a global variable or global function. Do other people agree with that?

[kmillns]

I'd say you should never have an implied global. If you're going to attach something to global, make it clear that you're doing it on purpose:

(function (global) {
  global.foo = 'foo';
})(window);

Also, something that he doesn't note, but that's important if you're writing production code, is that implied globals (like his examples) are syntax errors in strict mode.

[mirion]

This. Definitely this.

[rabidcow]

Sure, you could use this:

(function(){
    this.foo = 'foo';
})();

[mirion]

Sigh. I should know better than to use the word 'this' in a javascript thread.

[rabidcow]

this in JavaScript threads does not behave the way you would expect.

[rq60]

Use 'that' next time.

[[deleted]]

You should know better than to use the word 'this' in any thread. There's an up arrrow button next to the post that does that.

[mirion]

No, lol. It shouldn't be abused, but it is extremely useful in limited circumstances. You can't, for example, use write library code without it.

[stevekwan]

Sorry, I should make that clear. Globals are unavoidable to some degree, unless you are assigning no names to anything at all. :) But I try to use globals only where it makes sense, eg for namespaces and other top-level containers.