How to use JavaScript iterator?

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In JavaScript, processing of items is a very common procedure.
This language allows its users to perform a number of iterating processes over a large number from filter () to for loops as well as maps ().
This is a concept which is used in core JavaScript in order to customize the mechanism of for and of loops. Here, we are going to explain it in detail.

What is a JavaScript iterator?

First of all, we would like to explain what a JavaScript iterator is.
You can call an object an iterator, when it has abilities to access things from a collection of many things one at a time.
The best thing about it is that it will keep a track in sequence while keeping in mind its current location.

In this language, it is used as an object which will help you in delivering the next ().
The function of next () is to deliver the next item which will come in the sequence.
Now, you will get the return value in the form of two properties.
These are done and value.

In order to end this method, you have to call the object with its done property and then set it to be true.
Here, we would like to add that that you don’t have to make an iterator again and again.
This is because of the reason that you can use it again and again with the help of next () function. Now, we are going to share an example which will make your concept clearer:

function makeIterator(array) {
    var nextIndex = 0;
    return {
       next: function() {
           return nextIndex < array.length ?
               {value: array[nextIndex++], done: false} :
               {done: true};
       }
    };
}

Implementation of an iterator:

In order to implement an iterator, you have to keep in mind a few objects.
The range of these objects could be from two to three. These objects will conform the following interfaces:

  • Iterable interface
  • Iterator interface
  • IteratorResult interface

With the help of these interfaces, you are allowed to make your own custom iterators.
It will also allow you to traverse an iterable object with the help of for and of statement.

In the latest web pages, the developers are using many built in arrays which are now iterators.
The use of return method is also very common these days.
If you want to have full command over this language, then you need to learn it and implement it with the help of different ways.

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