6/12/2023 0 Comments For of loop javascript![]() Notice how 'c' in obj returns true even though the value of o.c is undefined. 'e' in obj //false (referenced but not assigned) 'c' in obj //true ('undefined' but still exists) ![]() The ES 5 specification details two distinct syntaxes for the for-in statement:ġ. This article attempts to fill some gaps, I hope its useful. There’s a bunch of literature about the dangers of using for-in to iterate arrays and when to apply the hasOwnProperty filter, but beyond that, documentation of this ubiquitous construct is surprisingly patchy. The for-in loop is the only cross-browser technique for iterating the properties of generic objects.
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