Exercises: Functions

To solve problems with code, you need to be able to break large problems into small ones. Usually, these smaller problems will take the form of functions that are used to solve the larger problem. Therefore, to solve problems with code, you need to be skilled at writing functions. And to master functions, you need to write a lot of them.

These exercises ask you to write many relatively small functions, which combine to form larger, more complicated ones.

At the end, you will be able to create strings of shapes, like this nifty diamond:

     #
    ###
   #####
  #######
 #########
 #########
  #######
   #####
    ###
     #

There is no starter code for these exercises, so create a new JavaScript file within your javascript-projects/functions directory to get started.

Rectangles

makeLine(size) function

Write a function makeLine(size) that returns a line with exactly size hashes.

console.log(makeLine(5));

Console Output

 #####

function makeLine(size) {
  let line = '';
  for (let i = 0; i < size; i++) {
    line += '#';
  }
  return line;
}

makeSquare(size) function

Write a function called makeSquare(size) that returns a size by size string of hashes. The function should NOT print each row of the square. Instead, it must return a single string that contains the entire shape.

console.log(makeSquare(5));

Console Output

 #####
 #####
 #####
 #####
 #####

makeRectangle(width, height) function

Write a function makeRectangle(width, height) that returns a rectangle with the given width and height. Use your makeLine function to do this.

console.log(makeRectangle(5, 3));

Console Output

 #####
 #####
 #####

function makeRectangle(width, height) {
  let rectangle = '';
  for (let i = 0; i < height; i++) {
    rectangle += (makeLine(width) + '\n');
  }
  return rectangle.slice(0, -1);
}

Now, go back and rewrite makeSquare to use makeRectangle.

Triangles

makeDownwardStairs(height) function

Write a function makeDownwardStairs(height) that prints the staircase pattern shown below, with the given height. Use your makeLine function to do this.

console.log(makeDownwardStairs(5));

Console Output

 #
 ##
 ###
 ####
 #####

function makeDownwardStairs(height) {
  let stairs = '';
  for (let i = 0; i < height; i++) {
    stairs += (makeLine(i+1) + '\n');
  }
  return stairs.slice(0, -1);
}

makeSpaceLine(numSpaces, numChars) function

Write a function makeSpaceLine(numSpaces, numChars) that returns a line with exactly the specified number of spaces, followed by the specified number of hashes, followed again by numSpaces more spaces.

console.log(makeSpaceLine(3, 5));

Console Output

___#####___

makeIsoscelesTriangle(height) function

Write a function makeIsoscelesTriangle(height) that returns a triangle of the given height.

console.log(makeIsoscelesTriangle(5));

Console Output

     #
    ###
   #####
  #######
 #########

function makeIsoscelesTriangle(height) {
  let triangle = '';
  for (let i = 0; i < height; i++) {
    triangle += (makeSpaceLine(height - i - 1, 2*i + 1) + '\n');
  }
  return triangle.slice(0, -1);
}

Diamonds

makeDiamond(height) function

Write a function makeDiamond(height) that returns a diamond where the triangle formed by the top portion has the given height.

console.log(makeDiamond(5));

Console Output

     #
    ###
   #####
  #######
 #########
 #########
  #######
   #####
    ###
     #

Bonus Mission

Refactor your functions so that they take a single character as a parameter, and draw the shapes with that character instead of always using '#'. Make the new parameter optional, with default value '#'.