I’m not sure how to title this question, but it’s concerning a pattern where the ||
operator is used to resolve a sequence of undefined values to the first defined one.
Are these equivalent?
export function getRuntime(): Runtime { return runtime || findWindow() || mockWindow; }
and
export function getRuntime(): Runtime { if (runtime) return runtime; if (findWindow()) return findWindow(); return mockWindow; }
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Answer
Both of the code snippets do the same thing, as the ||
and return
is simply doing the same thing as returning from the if
statements.
The only difference between the two is that if findWindow()
returns a value which is considered true
in JavaScript, it will run twice. This “issue” only occurs in the second one.