Project: Utility library

Overview of the 5-lesson utility library project: reusable structures with class + module.

Project: Utility library

In this 5-lesson project we'll build a reusable utility library. At its center is a Collection class: it brings adding, removing and searching together in one interface.

Our roadmap:

Lesson 1: set up the class skeleton
Lesson 2: set up the internal state with the constructor
Lesson 3: add the add, remove and find methods
Lesson 4: export the class as a module
Lesson 5: import the module from another file and use it

Each lesson continues from the previous one's solution.

The library skeleton

A library is the sum of units used from the outside. Our unit is a single class: Collection. It wraps an array and exposes access through methods; the items array is never touched directly from outside.

In this lesson we'll only declare the empty class and add a header comment to the file. Later lessons will fill it in. The class keyword is enough to start.

Exercise Declare the empty Collection class

Add a header comment to library.js and declare an empty Collection class.

Show example solution

Write class, a space, the class name, and curly braces.

Example solution:
// Utility library
class Collection {}

Test yourself

Which class brings adding, removing and searching into one interface?
- Promise
- Collection
- Fetch
- Array
Show answer

Collection — Correct! Collection is the central class of this project.
Declare the empty class
```
class ____ {}
```
Show answer
```
class Collection {}
```
Match each concept to its role

class

defines a class
constructor

sets up an instance
this

reaches internal state
export

opens to a module

Next lesson: Class skeleton

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