College Board Big Idea 1

Identifying and Correcting Errors (Unit 1.4)

Become familiar with types of errors and strategies for fixing them

• Review CollegeBoard videos and take notes on blog
• Complete assigned MCQ questions if applicable

Code Segments

Practice fixing the following code segments!

Segment 1: Alphabet List

Intended behavior: create a list of characters from the string contained in the variable alphabet

Code:

%%js

var alphabet = "abcdefghijklmnopqrstuvwxyz";
var alphabetList = [];

for (var i = 0; i < 26; i++) {
	alphabetList.push(alphabet[i]);
}

console.log(alphabetList);

<IPython.core.display.Javascript object>

What I Changed

I changed where the letters were appended to and made sure that letters were being appended

Segment 2: Numbered Alphabet

Intended behavior: print the number of a given alphabet letter within the alphabet. For example:

"_" is letter number _ in the alphabet

Where the underscores (_) are replaced with the letter and the position of that letter within the alphabet (e.g. a=1, b=2, etc.)

Code:

%%js

// Copy your previous code to built alphabetList here

let letterNumber = 2
var alphabet = "abcdefghijklmnopqrstuvwxyz";
var alphabetList = [];

for (var i = 0; i < 26; i++) {
	alphabetList.push(alphabet[i]);
}

console.log(alphabetList[letterNumber-1] + " is letter number " + letterNumber + " in the alphabet")

// Should output:
// "e" is letter number 5 in the alphabet

<IPython.core.display.Javascript object>

What I Changed

I changed…

Segment 3: Odd Numbers

Intended behavior: print a list of all the odd numbers below 10

Code:

%%js

let evens = [];
let i = 1;

while (i <= 10) {
  evens.push(i);
  i += 2;
}

console.log(evens);

<IPython.core.display.Javascript object>

What I Changed

I changed…

BELOW NOT EDITED

The intended outcome is printing a number between 1 and 100 once, if it is a multiple of 2 or 5

• What values are outputted incorrectly. Why?
• Make changes to get the intended outcome.

%%js

var numbers = []
var newNumbers = []
var i = 0

while (i < 100) {
    numbers.push(i)
    i += 1
}
for (var i of numbers) {
    if (numbers[i] % 5 === 0)
        newNumbers.push(numbers[i])
    else if (numbers[i] % 2 === 0)
        newNumbers.push(numbers[i])
}
console.log(newNumbers) 

<IPython.core.display.Javascript object>

Challenge

This code segment is at a very early stage of implementation.

• What are some ways to (user) error proof this code?
• The code should be able to calculate the cost of the meal of the user

Hint:

• write a “single” test describing an expectation of the program of the program
• test - input burger, expect output of burger price
• run the test, which should fail because the program lacks that feature
• write “just enough” code, the simplest possible, to make the test pass

Then repeat this process until you get program working like you want it to work.

%%js

var menu =  {"burger": 3.99,
         "fries": 1.99,
         "drink": 0.99}
var total = 0

//shows the user the menu and prompts them to select an item
console.log("Menu")
for (var item in menu) {
    console.log(item + "  $" + menu[item].toFixed(2)) //why is toFixed used?
}
//ideally the code should support mutliple items
var item = "burger"

//code should add the price of the menu items selected by the user 
console.log(total)

<IPython.core.display.Javascript object>

Hacks

Now is a good time to think about Testing of your teams final project…

• What errors may arise in your project?
• What are some test cases that can be used?
• Make sure to document any bugs you encounter and how you solved the problem.
• What are “single” tests that you will perform on your project? Or, your part of the project?
  • As Hack Design and Test plan action … Divide these “single” tests into Issues for Scrum Board prior to coding. FYI, related tests could be in same Issue by using markdown checkboxes to separate tests.