Lab 2 Solution

Modules and Error Checking

This week, you will be creating your first package and first module!

You will write 3 files this week + provide a package.json file; two of which will be modules, and one of which will use that module. You will submit them in a zip file named LastName_FirstName.zip . You should not have any folders inside the

zip file.

1. index.js: This file will require both geometry.js and utilities.js and will test each method you export 5 times.

2. geometry.js: This module will provide several methods to compute basic geometric formulas.

3. utilities.js: This module will provide several methods to perform basic utility methods.

4. package.json: This file will describe your package. You can accomplish most of the specified requirements with the npm init command (see below).

If an argument fails error checking, you should throw a string describing what's argument was wrong, and what went wrong.

Making a package

Make sure to initialize a package and name it cs-546-lab-2 for this lab! You can use npm init to help get this started.

You must also include a proper npm start task that will run index.js , and an author field in your package.json

file! The author field should have your first name, last name, and CWID.

geometry.js

This file will export 4 methods. Each method will have error checking on each argument.

volumeOfRectangularPrism(length, width, height)

This method will calculate the volume of a rectangular prism. You must check that each argument is provided, is a number, and is within proper bounds. surfaceAreaOfRectangularPrism(length, width, height) This method will calculate the surface area of a rectangular prism. You must check that each argument is provided, is a number, and is within proper bounds.




volumeOfSphere(radius)

This method will calculate the volume of a sphere. You must check that each argument is provided, is a number, and is within proper bounds. You must use Math.PI as the pi value.




surfaceAreaOfSphere(radius)

This method will calculate the surface area of a sphere. You must check that each argument is provided, is a number, and is within proper bounds. You must use Math.PI as the pi value.




utilities.js

This file will export 3 methods. Each method will have error checking on each argument.




deepEquality(obj1, obj2)

This method check each field (at every level deep) in obj1 and obj2 for equality. It will return true if each field is equal, and false if not.

For example, if given the following:

const first = {a: 2, b: 3};

const second = {a: 2, b: 4};

const third = {a: 2, b: 3};

console.log(deepEquality(first, second)); // false

console.log(deepEquality(first, third)); // true

You must check that each argument is provided and that each argument is an object.




uniqueElements(arr)

This method will iterate throughout the array provided in arr and return how many unique elements are in the array.

You must check that arr is provided and that it is an array. For example:

const testArr = ["a", "a", "b", "a", "b", "c"];

console.log(uniqueElements(testArr)); // outputs 3




countOfEachCharacterInString(str)

This method will traverse the string provided, str , and return an object. Each unique character in the array will be a key in the object, and the value will be how many times it appears in the string provided.

For example:

const test = "Hello, the pie is in the oven";

const charMap = countOfEachCharacterInString(test);

Would result in charMap having the value of:




{

" ": 6,

",": 1,

"H": 1,

"e": 5,

"h": 2,

"i": 3,

"l": 2,

"n": 2,

"o": 2,

"p": 1,

"s": 1,

"t": 2,

"v": 1

}

You must check that str is provided and that it is a string.




Requirements

1. You will have to write each function

2. You must submit all files, zipped up, not contained in any folders

3. You must not use any npm dependencies in this lab. You must do basic error checking in each function

1. Check for arguments existing and of proper type.

2. Throw if anything is out of bounds (ie, trying to perform an incalculable math operation or accessing data that

does not exist)