compile existence checks to existential operator about js2coffee HOT 6 OPEN

Would there be any issues if if (x) gets compiled into if x? ?

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In general? Yes. There are non-null falsey values in JS: false, 0, "", etc. It's the whole reason for the existential operators.

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if (x) => if x
if (!x) => unless x
if (x == null) => if x?
if (x === null) => if x?
if (x === void 0) => if x?
if (x !== void 0) => unless x?
if (typeof x == 'undefined') => if x?
if (typeof x != 'undefined') => unless x?

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if (x === null) => if x?
if (x === void 0) => if x?
if (x !== void 0) => unless x?

Wrong. Only cases where == is used or both checks for null and void ... are done should be converted to an existence check.

if (typeof x == 'undefined') => if x?
if (typeof x != 'undefined') => unless x?

Wrong. At the very least, these outputs should be reversed. Also, the || X == null check is also required because typeof null is "object" (soon to be "null").

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Thanks. I've personally never had the need to do a undefined/null/void check before, thanks for your guidance :)

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@rstacruz: See my commit comment about void operator safety.

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