Symbol iterator

The Symbol. The iterable protocol looks up this symbol for the method that returns the iterator for an object. Symbol iterator order for an object to be iterable, it must have an iterator key.

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Symbol iterator

Help to translate the content of this tutorial to your language! Iterable objects are a generalization of arrays. Of course, Arrays are iterable. But there are many other built-in objects, that are iterable as well. For instance, strings are also iterable. For instance, we have an object that is not an array, but looks suitable for for.. To make the range object iterable and thus let for.. Technically, we may merge them and use range itself as the iterator to make the code simpler. Now range[Symbol. But two parallel for-ofs is a rare thing, even in async scenarios. Infinite iterators are also possible. For instance, the range becomes infinite for range. Or we can make an iterable object that generates an infinite sequence of pseudorandom numbers.

Create Improvement. All iterator protocol methods nextreturnand throw are expected to return an object implementing the IteratorResult interface.

Iteration protocols aren't new built-ins or syntax, but protocols. These protocols can be implemented by any object by following some conventions. There are two protocols: The iterable protocol and the iterator protocol. The iterable protocol allows JavaScript objects to define or customize their iteration behavior, such as what values are looped over in a for Some built-in types are built-in iterables with a default iteration behavior, such as Array or Map , while other types such as Object are not. In order to be iterable , an object must implement the iterator method, meaning that the object or one of the objects up its prototype chain must have a property with a iterator key which is available via constant Symbol. A zero-argument function that returns an object, conforming to the iterator protocol.

Summary : in this tutorial, you will learn about the JavaScript symbol primitive type and how to use the symbol effectively. ES6 added Symbol as a new primitive type. To create a new symbol, you use the global Symbol function as shown in this example:. The Symbol function accepts a description as an optional argument. The description argument will make your symbol more descriptive.

Symbol iterator

The Symbol. Used by for The source for this interactive example is stored in a GitHub repository. Whenever an object needs to be iterated such as at the beginning of a for.. Some built-in types have a default iteration behavior, while other types such as Object do not. The built-in types with a iterator method are:. Or iterables can be defined directly inside a class or object using a computed property :.

Josef seibel

Confirm Unflag. In order to be iterable , an object must implement the iterator method, meaning that the object or one of the objects up its prototype chain must have a property with a iterator key which is available via constant Symbol. Lesson navigation Symbol. Share your suggestions to enhance the article. Code Editor Try it With our online code editor, you can edit code and view the result in your browser. Similar Reads. The iterator protocol defines a standard way to produce a sequence of values either finite or infinite , and potentially a return value when all values have been generated. For instance, we have an object that is not an array, but looks suitable for for.. Help to translate the content of this tutorial to your language! In order for an object to be iterable, it must have an iterator key. Pretty cool, right? You have the flexibility to make your iterator as simple or as complex and you want. Tutorial map. A function that accepts zero or one argument and returns an object conforming to the IteratorResult interface see below. Suggest changes.

Help to translate the content of this tutorial to your language! Iterable objects are a generalization of arrays. Of course, Arrays are iterable.

Can be omitted when done is true. The well-known symbol iterator. If this is a lot of understand right now that's completely expected. Lastly, to tie up one loose-end, for What is a Quiz? For example, the range in the example above is iterable, but not array-like, because it does not have indexed properties and length. Skip to main content Skip to search Skip to select language. Check out more JSBits at my blog, jsbits-yo. Examples might be simplified to improve reading and learning. We'll explain that more soon The problem with a home made iterable: It does not support the JavaScript for.. Stick with me! Exercises Test your skills with different exercises.