Time is a function I used to compute the speed of the execution. a for.of loop that iterates over a generator function that yields the values of the array.

a for.of loop that iterates the items of the array directly.a classic for.in loop that increments an index and reads the array at that index.The code tests the speed of adding all the items of a large array in three cases: So I went to test the performance of iterating itself. The difference between the two tests was that one was sorting inline (normal array reading and writing) and the other was using a more complex function and iterated a data source. On the test page I had amazing performance, on the other it was slow as hell. Every time you iterated over an array, for example, you have used iterators, but you can also iterate over Map objects and even over strings.So I was trying to optimize a sorting algorithm, only the metrics did not make any sense. Most likely, you have already used JavaScript iterators. After this section, it will become clear that generators are simply a way to write iterators more securely.Īs the name already gives away, iterators allow you to iterate over an object (arrays are also objects). What are iterators?īefore we can understand generators, we need a thorough understanding of iterators in JavaScript, as these two concepts go hand-in-hand. As a continuation of that, I want to explain how JavaScript’s iterators and generators work in this article. I always like to look at how things work under the hood: In a previous blog series, I explained how JavaScript works in the browser. The second part of this blog post focuses entirely on generators: what they are, how to use them, and in which situations they can be useful. In the first section, we will see how to use iterators and make any object iterable. Iterators allow you to iterate over any object that follows the specification. With the introduction of ES6, iterators and generators have officially been added to JavaScript.

JavaScript iterators and generators: A complete guide Felix Gerschau Follow Felix is a frontend developer at Fitogram in Cologne, Germany.

For iterator javascript