no-iterator.md

Pattern: Use of __iterator__ property

Issue: -

Description

The __iterator__ property is an obsolete SpiderMonkey extension that was used to create custom iterators. Modern JavaScript provides the Symbol.iterator protocol for creating iterable objects. Using __iterator__ reduces compatibility and maintainability.

Examples

Example of incorrect code:

Foo.prototype.__iterator__ = function() {
  return new FooIterator(this);
};

obj.__iterator__ = function() {
  // custom iterator
};

foo["__iterator__"] = function() {};

Example of correct code:

Foo.prototype[Symbol.iterator] = function() {
  return new FooIterator(this);
};

class MyIterable {
  *[Symbol.iterator]() {
    yield* this.items;
  }
}

const iter = {
  *[Symbol.iterator]() {
    yield 1;
    yield 2;
  }
};