cesarnml / eloquent-javascript-v4

Eloquent JavaScript by Marijn Haverbeke

Table of Contents

• Eloquent JavaScript by Marijn Haverbeke
  • Table of Contents
  • Contents
  • Notes
    • Introduction
    • Chapter 01: Values, Types and Operators
    • Chapter 02: Program Structure
    • Chapter 03: Functions
    • Chapter 04: Data Structures - Objects and Arrays

Contents

• Introduction [2024-04-22]
• Chapter 01: Values, Types and Operators [2024-04-22]
• Chapter 02: Program Structure [2024-04-23]
  • Exercises [2024-04-23]
• Chapter 03: Functions [2024-04-24]
  • Exercises [2024-04-24]
• Chapter 04: Data Structures - Objects and Arrays
  • Exercises
• Chapter 05: Higher-Order Functions
  • Exercises
• Chapter 06: The Secret Life of Objects
  • Exercises
• Chapter 07: Project - A Robot
• Chapter 08: Bugs and Errors
  • Exercises

Notes

Introduction

• A couple choice quotes from the book's intro:

"Because computers are dumb ... programming is fundamentally tedious and frustrating."

"[Programming] is a wonderful game of puzzle solving and abstract thinking."

"You are fine -- you just need to keep at it."

"A program is a building of thought."

"The best programs are those that manage to do something interesting while still being easy to understand."

"There are many terrible mistakes to make in program design, and you should go ahead and make them at least once so that you understand them. A sense of what a good program looks like is developer with practice, not learned from a list of rules."

"There are those who will say terrible things about JavaScript. Many of these things are true."

"JavaScript is ridiculously liberal in what it allows."

• Trivia: ECMAScript6 was released in 2015

Book Website

Chapter Exercise Code

Chapter 01: Values, Types and Operators

• Five of the primitive types in JavaScript:
  • 1. number
    • Three special numbers: Infinity, -Infinity, NaN
    • Trivia: Only NaN == NaN // false (not equal to itself)
  • 2. string
  • 3. boolean
  • 4. null
  • 5. undefined
• JavaScript uses 64-bits to represent numbers (9e9 positive/negative numbers)
• JavaScript uses 16-bits for strings (which causes emojis to take up two characters 🤦‍♂️)
• Uppercase letters are always less than lowercase letters
• type coercion is the root of all evil

Chapter 02: Program Structure

• Summary: Most of this chapter involves presenting rather basic and easy to grok aspects of the language syntax.

"a do loop always executes its body at least once, and it starts testing whether it should stop only after that first execution."

"a program is built out of statements ... statements tend to contain expressions ... you can introduce disturbances in the flow of control by using conditional (if, else, and switch) and looping (while, do, and for)"

Chapter 03: Functions

• Summary: This chapter touches on several fundamental concepts surrounding JavaScript functions:
  • the concept of purpose (encapsulation and abstraction)
  • the concept of hoisting, binding lexical scope and closure
  • the 3 ways to declare a function in JS (function keyword statement, expression and arrow function declaration)
  • it also discusses the Call Stack, recursive functions, and premature optimization
  • pure vs side-effect based functions
  • local vs global bindings

"Functions are a way to structure larger programs, to reduce repetition, ... to isolate [pieces of code from each other]."

"Functions have parameters and a body."

"Each binding has a scope, the part of the program in which the binding is visible."

"Being able to reference a specific instance of a local binding in an enclosing scope -- is called a closure. A function that references bindings from local scopes around it is called a closure."

"A good mental model is to think of a function values as containing both the code in their body and the environment in which they are created ... The function body sees the environment in which it was created, not the environment in which it is called.

• A function that calls itself is called recursive

Chapter 04: Data Structures - Objects and Arrays