ECMAScript Generator Basics

Generator in ECMAScript 2015 – Part 1

ECMAScript 6

Foreword: In this part of the series, I give you the basics of ECMAScript generator.

By: Chrysanthus Date Published: 21 Jul 2016

Introduction

In this part of the series, I give you the basics of ECMAScript generator. A collection is an array or a set or a map. In ECMAScript, generator is a way of creating and iterating a custom collection.

Example
Imagine a class of 5 students who wrote a test. 3 students had marks; one student was absent and the result of one was cancelled. The marks (result) may be written as follows:

56
70
'absent'
60
'cancelled'

This is a collection.

Creating a Custom Collection
You can create a custom collection in two ways. You can create the above collection like,

    function* myCollection()
        {
            yield 56;
            yield 70;
            yield 'absent';
            yield 60;
            yield 'cancelled';
        }

or like,

    function* myCollection()
        {
            yield* [56, 70, 'absent', 60, 'cancelled'];
        }

Note the use of the asterisk. myCollection is a name of your choice, while function is a reserved word. yield is also a reserved word.

Iterating through the Collection
The following for-loop iterates through the collection:

    for (item of myCollection())
        alert(item);

Note the use of “item of” where item is a variable name of your choice.

That is it for this part of the series.

Chrys

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