for in loops over enumerable property names of an object. for of (new in ES6) does use an object-specific iterator and loops over the values generated by that. In your example, the array iterator does yield all the values in the array (ignoring non-index properties).

Nov 20, 2024 · The JavaScript for-in loops through the enumerable properties of an object. The loop will iterate over all enumerable properties of the object itself and those the object inherits from its constructor’s prototype.

Oct 28, 2008 · for...in is perfectly appropriate for looping over object properties. It is not appropriate for looping over array elements. If you can't understand the difference between these scenarios, then yes, you should avoid for...in; otherwise, go nuts.

Dec 29, 2014 · for (... in ...) is typically used to iterate through the properties of objects (which are what javaScript uses for associative arrays), while the typical for loop is used for sequential arrays.

Feb 20, 2019 · Syntactic Overview The for and for/in looping constructs give you access to the index in the array, not the actual element. For example, suppose you want to print out the values stored in the below array: const arr = ['a', 'b', 'c']; With for and for/in, you need to print out arr[i]: for (let i = 0; i < arr.length; ++i) { console.log(arr[i]); }

Jul 12, 2023 · Both for...in and for...of are used to loop over elements in an iterable object, like an array, string, or object. While they may seem similar, they have some key differences. for...in is...

Nov 11, 2021 · for...of loop works only with iterable objects. In JavaScript, iterables are objects which can be looped over. String, Array, TypedArray, Map, and Set are all built-in iterables, because each of their prototype objects implements an @@iterator method. So, for...of loop works on the mentioned object types.

Use for…in when you need to iterate through an object’s properties, including inherited ones; Use for…of when you want to loop through iterable objects like arrays, strings, maps, or sets;

Learn the key differences between for...in and for...of loops in JavaScript, including their syntax, use cases, and examples.

Feb 4, 2021 · In this article, I am explaining the differences between the four for loops in JavaScript. The best use for these loops is as follows: For arrays, use for...of (or forEach). If …