Axel Rauschmayer wrote:
1. Both undefined and null [not too much of a problem, easily learned]
2. Truthy and falsy values [not pretty, but I’ve grown used to them
and the convenient but sloppy “has a value” checks via `if`]
These are usually winning. Dart makes you be explicit in testing and
convering, it's a pain from what I can tell.
ToBoolean implicit conversions usually DWIM. The ToNumber, ToInt32, and
ToUint32 conversions more often go wrong.
3. == [easy fix: always use ===]
4. Parameter handling [fixed in ES6]
5. Array-like objects [not completely fixed (DOM...), but `arguments`
becomes obsolete in ES6]
6. Function-scoped variables [`let` FTW in ES6]
7. Accidental sharing of data [for-of will help in ES6]
8. Creating sub-constructors is messy [fixed via classes and `super`
in ES6]
9. `this` in non-method functions:
9a) Referring to the `this` of a surrounding method,
9b) accidentally creating globals by forgetting `new`,
9c) using methods as callback functions
[(a) and (b) fixed by ES6 arrow functions and ES5 strict mode]
10. The for-in loop [simple rule: avoid if you can, already possible
in ES5]
Thus: 1-3 won’t go away soon. 4-10 are mostly eliminated by ES6.
Deliberate omissions:
- Implicit conversions are messy (and a superset of pitfall #2), but
seem to surprise people much less than the above items.
I think you have it backwards.
- Modules close another important hole in JavaScript, but I wouldn’t
consider that hole a pitfall.
You mean free variables being static errors? That is not a done deal yet.
Missing properties yielding undefined still burns many JS programmers.
Not an implicit conversion, so worth a separate item.
/be
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