Eloquent Javascript Book: Exercise Answers

Eloquent Javascript Exercise Answers

/* 
  These are my attempts at the exercises in the book Eloquent Javascript
  http://eloquentjavascript.net
*/

EloquentJS_Chap02_01ChessBoard.js

var size = 8;

for (var row = 1; row <= size; row++) {
  var line = "";
  for (var col = 1; col <= size; col++) {
    // Key to this problem is adding up the row number and col number of a particular square.
    if ((row + col) % 2 === 0) {
      line += " ";
    } else {
      line += "#";
    }
  }
  console.log(line);
}

EloquentJS_Chap02_02FizzBuzz.js

/*
  Question at http://eloquentjavascript.net/02_program_structure.html
*/

for (i = 1; i <= 100; i++) {
  if (i % 3 === 0 && i % 5 === 0) {
    console.log("FizzBuzz");
  } else if (i % 3 === 0) {
    console.log("Fizz");
  } else if (i % 5 === 0) {
    console.log("Buzz");
  } else {
    console.log(i);
  }
}

EloquentJS_Chap02_03Triangles.js

/* 
  Write a loop that makes seven calls to console.log to output the
  following triangle:

  #
  ##
  ###
  ####
  #####
  ######
  #######
*/

var line = "";
for (var i = 0; i < 7; i++) {
  line += "#";
  console.log(line);
}

EloquentJS_Chap03_01Minimum.js

function min(x, y) {
  if (x <= y) {
    return x;
  } else {
    return y;
  }
}

EloquentJS_Chap03_02Recursion.js

function isEven(x) {
  // Convert any negative integers to positive
  if (x < 0) {
    x *= x;
  }
  if (x === 0) {
    return true;
  } else if (x === 1) {
    return false;
  } else {
    return isEven(x - 2);
  }
}

EloquentJS_Chap03_03BeanCounting.js

// Is "string" an acceptable parameter name?
function countBs(string) {
  var numBees = 0;
  for (var i = 0; i < string.length; i++) {
    if (string.charAt(i) === "B") {
      numBees += 1;
    }
  }
  return numBees;
}

function countChar(string, char) {
  var numChars = 0;
  for (var i = 0; i < string.length; i++) {
    if (string.charAt(i) === char) {
      numChars += 1;
    }
  }
  return numChars;
}