jwbraith / eloquence

going through the eloquent javascript book over the holidays

eloquence

going through the eloquent javascript book over the holidays

Chapter 2: Program Structure

// Looping a Triangle
let triangle = "";
do {
  triangle += "#";
  console.log(triangle);
} while (triangle.length < 8);

// Fizzbuzz
for (let i = 1; i <= 100; i++) {
  if (i % 5 == 0 && i % 3 == 0) {
    console.log("fizzbuzz");
  } else if (i % 5 == 0) {
    console.log("fizz");
  } else if (i % 3 == 0) {
    console.log("buzz");
  } else {
    console.log(i);
  }
}

//Chessboard
let size = 8;
let board = "";

for (let j = 0; j < size; j++) {
  if (j % 2 == 0) {
    for (let i = 0; i < size; i++) {
      if (i % 2 == 0) {
        board += "#";
      } else {
        board += " ";
      }
    }
  } else {
    for (let i = 0; i < size; i++) {
      if (i % 2 == 0) {
        board += " ";
      } else {
        board += "#";
      }
    }
  }
  board += "\n"
}
console.log(board);

Chapter 3: Functions

// Minimum
let minuo = (a, b) => {
  if (a < b) {
    return a;
  } else {
    return b;
  }
}
console.log(minuo(22, 33));
console.log(Math.min(22, 33));

// Recursion
let isEven = (n) => {
  if (n == 0) {
    return true;
  } else if (n == 1) {
    return false;
  } else {
    return isEven(n - 2);
  }
}
console.log(isEven(50));
console.log(isEven(65));

// Bean Counting
let word = "Beanboozled";
let char = 'o'
let countChar = (word, char) => {
  let numOfChar = 0;
  for (let i = 0; i < word.length; i++) {
    if (word[i] == char) {
      numOfChar++;
    }
  }
  return numOfChar;
}
console.log(word + " has " + countChar(word, char) + " many \"" + char + "\"s");

Chapter 4: Objects & Arrays

// The Sum of a Range
let range = (start, end, step = 1) => {
  let rangeOfNum = [];
  if (end > start) {
    for (let i = start; i <= end; i += step) {
      rangeOfNum.push(i);
    }
  } else {
    for (let i = start; i >= end; i += step) {
      rangeOfNum.push(i);
    }
  }

  return rangeOfNum;
}
console.log(range(5, 2, -1));

let sum = (summands) => {
  let total = 0;
  summands.forEach(element => {
    total += element;
  });
  return total;
}
console.log(sum(range(1, 10))); // 55

// Reversing an Array
let reverseArray = (arr) => {
  let retArr = [];
  for (let i = 0; i < arr.length; i++) {
    retArr[i] = arr[arr.length - (1 + i)];
  }
  return retArr;
}
let example = [12, 24, 48, 96, 192];
console.log(reverseArray(example));

let reverseArrayInPlace = (arr) => {
  let revArr = [];
  for (let i = 0; i < arr.length; i++) {
    revArr.unshift(arr[i]);
  }
  for (let i = 0; i < revArr.length; i++) {
    arr[i] = revArr[i];

  }
  return arr;
}
console.log(example);
console.log(reverseArrayInPlace(example));

// A List (A list?)
let arr123 = [1, 2, 3];
let arrayToList = (arr) => {
  let list = {};
  list.value = arr.shift();
  if (arr.length > 0) {
    list.rest = arrayToList(arr);
  } else {
    list.rest = null;
  }
  return list;
}
let list123 = (arrayToList(arr123));
console.log("the resultant list is ");
console.log(list123);

let listToArray = (list) => {
  let arr = [];
  for (let node = list; node; node = node.rest) {
    arr.push(node.value);
  }
  return arr;
}
console.log("the list turned back into an array is ");
console.log(listToArray(list123));

let prepend = (element, inputList) => {
  let list = { element, rest: inputList };
  return list;
}
list123 = prepend(6, list123);
console.log("after prepending the list is ");
console.log(list123);

let nth = (list, num) => {
  if (!list) {
    return undefined;
  } else if (num == 0) {
    return list.value;
  } else {
    return nth(list.rest, num - 1);
  }
}
console.log(nth(list123, 3));

// Deep Comparison
let deepEqual = (comparer, comparand) => {
  if (comparer === comparand) {
    return true;
  }
  if (comparer == null || typeof comparer != "object" || comparand == null || typeof comparand != "object") {
    return false;
  }
  let keysA = Object.keys(comparer), keysB = Object.keys(comparand);
  if (keysA.length != keysB.length) {
    return false;
  }
  for (let key of keysA) {
    if (!keysB.includes(key) || !deepEqual(comparer[key], comparand[key])) {
      return false;
    }
  }
  return true;
}
let scar = { face: "slash" };
let chin = { face: "butt" };
console.log(deepEqual(scar, chin));