JavaScript Day 3 Warm-up!

Instructions:

1. Function Drills

For each of these functions, do the following:

1. Identify the function name, the function's inputs (name/value) (parameters) and the function's outputs (name/value) (things that are returned).
2. Describe what the function does in plain English.

function sayHello() {
  console.log("hello world");
}

function logTwoNumbers(first, second) {
  var sum = first + second;
  console.log(sum);
}

function addTwoNumbers(first, second) {
  var sum = first + second;
  return sum;
}

What's the difference between console.log(sum) and return sum?

Try typing the following in your console:

var result = logTwoNumbers(1, 2);
result;

var sum = addTwoNumbers(1, 2);
sum;

Note that result is undefined, while sum is 3. Returning a result allows you to capture the result in a variable. Using console.log simply prints out the result on the console, but it can't be saved into a variable.

2. Conditional Drills

Given these variables:

var bigNum = 1000;
var smallNum = 2;

1. Use the equals === operator to make a false statement and a true statement, and console.log the results

2. Use the less than < operator to make one true statement and one false statement, and console.log the results

3. Use the greater than > operator to make one true statement and one false statement, and console.log the results

4. Use the not equals != operator to make one true statement and one false statement, and console.log the results

3. Code Reading

DO NOT RUN THESE CODE EXAMPLES!!

The following is an exercise in reading code. Try to answer the following questions by only reading the code, without actually running it!

1. What is the output of the following code?

for (var i = 1; i <= 4; i++) {
  console.log("*");
}

var x = "|";
for (var i = 1; i <= 4; i++) {
  x = x + "*";
}
x = x + "|";
console.log(x);

for (var j = 1; j <= 3; j++) {
  var x = "|";
  for (var i = 1; i <= 4; i++) {
    x = x + "*";
  }
  x = x + "|";
  console.log(x);
}

2. What is the output of the following code?

function touch(elbow, ear) {
  console.log("touch your " + ear + " to your " + elbow);
}

var head = "shoulders";
var knees = "toes";
var elbow = "head";
var eye = "eyes and ears";
var ear = "eye";
      
touch(ear, elbow);
touch(eye, ear);
touch(head, "knees " + knees);

4. Code Writing

1. Write a function called myName that simply returns your name as a string.

• Store that string in a variable called thisIsMyName
• Log the value of that variable to the console.

2. Write a function called greeting that:

• Takes 1 argument: the hour of the day (24 hour time)
• Logs to the console "Good day" if the hour is less than 18, or "Good evening" otherwise.
• For example, greeting(10) should log "Good day", and greeting(20) should log "Good evening".
• Extra credit: Do not print anything when the hour parameter is invalid, such as greeting(24), greeting("hello"), or greeting(). (Decimals are OK, e.g. greeting(17.9) should log "Good day").

3. Write a function called receipt that:

• Takes 1 argument, the subtotal (total cost of the meal, without tax or tip)
• Returns the total cost, based on a 9% tax and a 15% tip.
• For example, receipt(20) should return 24.8.

5. Extra Credit

Complete these if you have extra time and want to take on a challenge!

1. Modify your receipt function in the following ways:

• Take an additional argument, tip, to specify the percentage of tip to leave. For example, receipt(20, 10) should return 23.8.
• Replace the subtotal argument with an array called costsPerItem, which is an array containing the prices for each item ordered in the meal.
  • Compute the subtotal from the costsPerItem array and calculate the total cost with tax and tip.
  • Round to the nearest cent.
  • For example, receipt([10, 9, 25], 20) should return 56.76.

2. Write a function called splitTheBill that:

• Takes 2 arguments, the total cost (i.e. with tax and tip included), and an array of string names (e.g. ["Victoria", "Jessie", "Joseph"])

• For each person, logs to the console the amount that they owe in the form of "[name] owes $[money]"

• Splits the amount owed per person as evenly as possible among the number of people.

• Note that money cannot exceed 2 decimal places (e.g. you cannot have $12.255) and the sum of each part should still add exactly up to the total cost.

• For example, splitTheBill(122.27, ["Victoria", "Joseph", "Jessie"]) should print:

  "Victoria owes $40.76"

  "Joseph owes $40.76"

  "Jessie owes $40.75"

View this lesson on Learn.co