This repository presents solutions to the exercises in the third edition of Marijn Haverbeke's Eloquent JavaScript (ISBN 978-1-59327-950-9).
Obviously my solutions are not the only possible solutions to the exercises presented in Marijn's book. Feel free to devise your own, perhaps better, approaches. In many cases, my code is a straight copy of the code presented in the book. Where I wanted to do so, I have modified things to better match my own style. With admitted hubris, in some cases I think my examples are more 'eloquent' but be your own judge please.
What follows are instructions for using running these exercise solutions. These instructions are biased towards Mac OS but should pretty much work the same for any Unix-like operating system where you have command line access. They should also be pretty close for Microsoft Windows, but I have not tested them that way. If you're so inclined and find problems, your submission of a pull request to this repository to correct the issue would be appreciated. Also, if you find any errors, please submit either an issue or a pull request correcting the problem.
I have sprinkled more external links in these instructions than would perhaps be normal. It's just my attempt to try to make using these examples easy for a beginner.
Clone this GitHub repo to your development computer. Refer to GitHub tutorials as there are several ways to do this.
While working on this project, I used Visual Studio Code as my code editor and cloned the repo using VSCode's built-in GitHub integration.
Whichever editor you use, these instructions assume you clone this repository to a code subdirectory of your home directory (i.e. ~/code). If you use a different subdirectory, you will need to change ~/code in the example commands to the path to which you cloned the repo where necessary.
If you haven't already done so, you will also need to have Node.js installed. While some of these examples could in theory be run from the console in any browser, using Node lets us easily also run a small web server for the Chapter 13 exercises and beyond. There are numerous online tutorials and training materials for how to install NodeJS so I won't duplicate that information here. Installing NodeJS should also automatically install the Node Package Manager (NPM).
Once you have cloned the repo and installed NodeJS along with NPM, you can check your installation. From a shell command prompt, you should be able to execute something like this (although the version numbers may differ):
$ cd ~/code/eloquentjs
$ node --version
v14.17.0
$ npm --version
v6.14.13Now that you know NodeJS and NPM are both installed, you need to install a few JavaScript package dependencies. These examples assume the Express framework is installed along with one or two additional packages. The package.json file tells NPM what packages to install, so installing the packages is as simple as:
$ npm installAs mentioned, these solutions were written to be run within the Node.js runtime environment. Once you have cloned this repository and installed NodeJS and the Express framework, you should be able to run the exercise solutions.
After installing Node.js and downloading this repository, to run an exercise simply run node with the exercise name as a parameter from a terminal prompt after changing the directory to where you locally installed the repository. For example, assuming you are using Mac OS and have it installed on a folder called eloquentjs under a folder called code, you would:
$ cd ~/code/eloquentjs
$ node chapter01/helloworld.js
Hello World!The exercises for Chapter 13 through XX utilize a NodeJS server and the Express framework. To support running these exercises, there a basic web server is provided in the resources directory. To use this server to run an exercise, first use the following:
$ cd ~/code/elequentjs
$ node resources/serve chapter13/hello
Browse to http://localhost:6502 to see the exercise solution "chapter13/hello"
To exit, press 'Ctrl-C'Then browse to http://localhost:6502 in your favorite browser to view the exercise solution. When done running the exercise, terminate the server by pressing 'Ctrl-C' in the terminal.
The exercise solutions attempt to only use the concepts that have been introduced up to that point in the book. For example, chapter one solutions to not use functions since functions are introduced in chapter two. So, if you're an expert and think "there is a better way" when looking at a solution please keep in mind that your concept might not have been introduced to the reader yet.
- helloworld.js - A bonus since chapter one does not have any exercises. But, we might as well say, "Hello!"
- triangle.js - Outputs a triangle to the console
- fizzbuzz.js - Outputs the classic Fizz buzz game and FizzBuzz programming interview question for numbers from 1 to 100
- chessboard.js - Outputs an NxN chessboard pattern to the console (the dimension is coded into the program)
- minimum.js - Implement min(), a basic Math.min function
- recursion.js - Demonstrates recursion by using a recursive isEven() function to determine if a number is even
- beancount.js - Implements a function, countLetters(), to count letters in a string and a second function, countBs(), to count the number of uppercase letter 'B's in a string
- deepcompare.js - Implements a deep comparision of equality between two objects
- list.js - Implements functions to manipulate a list data structure (single linked)
- range.js - Implements functions to create a range of numbers and sum and array
- reverse.js - Reverses the elements of an array using two approaches
- flatten.js - Flattens arrays into a single array
- loop.js - A custom loop that tests and updates while processing
- every.js - Tests to see if all elements in an array pass a test
- dominant.js - Determines the dominant writing direction in a string of text
- vector.js - Defines a vector class
- groups.js - Defines a 'groups' data structure that is similar to the standard JavaScript set data structure
- iterable.js - Extends 'groups' so that it is iterable
- borrow.js - Illustrates how to borrow a method from another object
- measure.js - Compares the performance of two robots
- efficient.js - Defines a more efficient robot
- persistent.js - Defines a persistent group
- retry.js - Implements a retry capability to retry a failing function until it succeeds
- lockbox.js - Handles accessing a box while preserving its states
- regexgolf.js - Short regex for selected string tests
- quotestyle.js - Single to double quote replacement
- numbers.js - JavaScript number matching
- modulerobot.js - A discussion of module organization of the robot project
- roads.js - CommonJS Module for the array of roads. Also includes an ES6 style version as a block comment
- circular.js - circular dependencies
- crowscalpel.js - Implements ansyn 'locateScalpel' function
- promiseall.js - A promise that waits for all the other promises to succeed
- eggsamples.js - Text provided sample programs using the base Egg interpreter
- arrays.js - Adds support of arrays to the base Egg interpreter
- closure.js - Explains how closures work in the base Egg interpreter
- comments.js - Adds comment support to the base Egg interpreter
- fixedscope.js - Adds a new 'set' special form
Chapter thirteen has no exercises. The solution here lays groundwork for the browser-based solutions going forward by providing a Node-based web server to serve the HTML, CSS, and JavaScript files along with any other assets.
- hello/ - Another "Hello World" to illustrate using the node web server provided for viewing web-based exercises
- examples/ - Compilation html, css, and scripts for the examples in each of the text sections for reference
- table/ - Dynamically builds a table of mountains
- elements/ - Manual implementation of document.getElementsByTagName
- catshat/ - The cat and the hat
- ballon/ - Displays a balloon that can be inflated and deflated with arrow keys but don't over inflate
- mousetrail/ - Mouse trails following the mouse
- tabs/ - Simple tabbed interface
- lightblue/ - EloquentJS's version of Thomas Palef's Dark Blue game by leveraging author's provided code as modules
- gameover/ - Implements a life maximum and game ends when all lives are lost
- gamepause/ - Implements the ability to pause a game [Not yet working!!]
The sources in this section, with the exception of the web server, are mostly direct copies from the book and are used to support some of the presented solutions. Where they are different, it is out of style changes mainly. There are some things that I prefer over Marijn's approach. But, who am I to know which is best. :-)
- scripts.js - leveraged by dominant.js
- meadowfield.js - implementation of the robot project from chapter 7 made into a module for usage by chapter 7 solutions
- egg.js - The base implementation of the Egg language
- crowtech.js - resources needed for chapter 11 exercises
- serve.js - A minimalist Express framework based web server for chapter 13 and beyond exercises
- template/ - Blank index.html, style.css, and scripts.js template files for starting new exercise projects
- blueengine/ - Contains all the author provided code made into modules for usage by chapter 16 solutions
Bonus things developed while working through the exercises
- tictactoe/ - BONUS: A basic Tic-Tac-Toe implementation [Not yet working!!]