CODEWITHSUNDEEP
javascriptarraysecmascript-6
tristantzara
tristantzara

Reputation: 5907

Is using for ...of for arrays ok?

Now we have a for... of loop in JS. Can it be used for iteration over arrays instead of for (let i = 0, len = array.length; i < len; i++) {...} seamlessly or are there any caveats that make using it for arrays a bad practice?

Upvotes: 1

Views: 120

Answers (3)

Oriol
Oriol

Reputation: 288530

Yes, it's OK.

Well, unless you specified a custom value for Symbol.iterator, but still want the loop to be from 0 to length.

var arr = [1,2,3,4];
arr[Symbol.iterator] = function*() {
  yield "custom";
  yield "iterator";
};

console.log('Old for loop:');
for (let i = 0; i < arr.length; i++) console.log('    ', arr[i]);

console.log('New for-of loop:');
for (let item of arr) console.log('    ', item);

Upvotes: 2

joews
joews

Reputation: 30330

Yes, for... of is fine for Arrays because they are iterable.

You can verify that in your browser's console by checking that Array instances have a Symbol.iterator method:

[][Symbol.iterator]
> values() { [native code] }

... and, tautologically, by the fact that you can iterate them with for... of!

Upvotes: 1

Michał Perłakowski
Michał Perłakowski

Reputation: 92579

In my opinion the main purpose of for-of loops is to iterate arrays. The fact that iterating arrays using for-in loops is considered a bad practice has nothing to do with it. Also, for-in loop can be used for iterating any objects, but for-of loop can be used only for iterating objects that are iterable.

Upvotes: 0

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