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 < 10; i++) {
	alphabetList.push(alphabet[i]);
}

console.log(alphabetList)

<IPython.core.display.Javascript object>

What I Changed

I changed it so now there is one array, and it pushes alphabets index rather than the index as a number

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

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

for (var i = 0; i < 10; i++) {
	alphabetList.push(alphabet[i]);
}

console.log(alphabetList)

let letterNumber = 5

for (var i = 0; i < alphabetList.length; i++) {
	if (i === letterNumber) {
		console.log(alphabetList[i-1] + ` is letter number ${i} in the alphabet`)
	}
}

What I Changed

I changed the for loop now to iterate through the alphabet array’s length and to reference the letters index value rather than the index itself and used a ${} to embed the index without having to use a + operator

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);

What I Changed

I changed the script to start at 1 instead of 0.

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 i = 0

while (i < 101) {
        if(i % 5 === 0  | i % 2 === 0)
        {
         numbers.push(i)   
        }
       
    i += 1
}
console.log(numbers) 

What I changed

I changed the code to now work without a for loop, the while loop to iterate until 101, and combined the if statments into one

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)) //toFixed makes it only have 2 decimal places
}
//ideally the code should support mutliple items
var order = ["burger","drink","fries"]


//code should add the price of the menu items selected by the user 
for(let i=0;i<order.length;i++)
  {
    let price = menu[order[i]]
    let decimalPlace = (price + "").split(".")[1];
    if(parseInt(decimalPlace) == 99) //4.99 = 5
    {
      price = Math.round(price)
    }
    total += price
  }
console.log(total.toFixed(2))
//

What I Changed

I explained that to fixed is for decimal places, I then made order an array to support multiple choices Then finally I added an additional line to round any prices that were ending in .99 to the next dollar

Hacks

Fix the errors in the first three segments in this notebook and say what you changed in the code cell under “What I Changed” (Challenge is optional)