Rediscovering JavaScript

Chapter 4

Here are the solutions to the ​Exercises​, for the Chapter 4, ​Iterators and Symbols​ chapter.

Exercise 1

const letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];

for(const [i, letter] of letters.entries()) {
  if(i % 3 === 0)
    console.log(letter);
}

Exercise 2

const numbers = [1, 2, 3];

console.log("The Symbol properties in arrays are:");

console.log(
  Object.getOwnPropertySymbols(Object.getPrototypeOf(numbers)));

Exercise 3

class Message {
  constructor(text) { this.text = text; }

  [Symbol.replace](word, substitute) {
    return this.text.replace(word, substitute);
  }
}

const message = new Message('There are no stupid questions.');

console.log('stupid'.replace(message, ...