👋 Hi Everyone! Here you will find similar challenges to the two that Noah created to help you learn Python. Since you will already have a good idea how to solve the two existing challenges, they were tweaked slightly to introduce new challenges.
❗ Before starting these challenges, you should read over this Mozilla Developer Network JavaScript basic article. The MDN web docs are an amazing resource where you can find many answers to common questions.
There are a few NPM dependencies that will be needed for your software to run.
There is one that helps us read from the terminal or console called
readline-sync. Then there are two development dependencies one to help us test
our code, and another to help make it pretty. These should be installed before
going much farther.
Type the following in the same directory as the code at the command line. If you have the code open in WebStorm you can click the "Terminal" tab at the bottom.
npm installOften when people write software and code, they will write more code that tests their code. One type of test that is written is the Unit Test. A Unit Test is targeted at testing the smallest testable parts of code. This is most often the function or method.
Both of the two challenges below have Unit Tests already written for them. When you write your tests before writing your code, it's called Test-Driven Development (TDD)! It's really handy to run these tests as you are writing your software. Pick a test case then write some code to make it pass, then pick the next and before you know it you have working software. Or you can use the tests after writing your code to validate that it does the right thing.
The included tests will be used to verify that you've completed the software correctly.
At the command line we can use NodeJS's build and dependency management tool to execute these tests.
Run All Tests
npm testRun Just the Calculator Tests
npm test -- calculator.test.jsRun Just the High Low Game Tests
npm test -- calculator.test.jsMentioned before is that there is a dependency included to help us format our code. Consistent code style is very important ease reading and enhance collaboration. If two people format their code in different ways it's hard to integrate them together and potentially could lead to bugs.
You can format any of your code at any type by typing the following at the command line.
npx prettier -w .Let's rewrite your Python three digit integer calculator in Javascript. Like in
original. We will be writing some code that parses a string that is structured
as a three digit integer, followed by a space, an arithmetic operator, another
space, and then another three digit integer. The code should then evaluate the
expression. For example, if "-200 + 150" is given the calculated result would
be -50. Another example would be "100 / 400" with the result being 0.25.
The number on either side of the operator must always be given as a 3 digit
integer, left padding the integer with zeros to make it 3 digits is allowed. For
example "005" and "075" are valid. You can look at the list of tests
calculator.test.js for more examples of valid and invalid
expressions.
Take a look at the file called calulator.js. There are two functions. You should complete these two functions (don't rename them, the test cases rely on them being named). Just start typing your code in them.
{
parse: function (expression) {
// TODO: Write a function that parses the given expression
return null;
},
solve: function (expression) {
// TODO: Write a function that uses the `parse(expression)` function
// to calculate the result
return 0;
},
}The first function parse(expression) should take an expression and return a
value that can be used to solve the result. For example, maybe it returns an
"array" containing the three tokens. Another option would be to return a
JavaScript object containing the three tokens. Regardless of what is
returned for a parsed expression. If that expression cannot be parsed, you
should return a null or other falsy value to indicate an error.
The second function solve(expression) should take an expression, then use the
parse(expression) function to parse it, and finally evaluate the result
returning it from the function. If the expression cannot be parsed, return a
null to indicate an error.
The run loop has already been written for you. You can try your calculator out by typing the following at the command line.
npm run calcAgain just like the first challenge, let's rewrite the High/Low game in JavaScript. This is a game were you are asked to guess a number between 1 and 100 while only being told if your guess is higher or lower than the target.
Take a look at the high-low.js file. There are 4 TODO comments. In addition to these functions, variables and TODO comments, you will find lots of documentation describing the expected behavior of each function.
You can run the game by typing the following at the command line. However for this challenge you will need to complete the game loop as well.
npm run high-lowComplete each TODO as described by the function documentation and use the
tests in high-low.test.js as a guide.
Consider the signup process forQRTrace ...
Q: Do we want users signing up with email addresses that clearly aren't valid? What about verification links? Suppose a user just misses a single character in their address, e.g., first.last@gmailcom...
No.
Q: Do we want users using super weak and insecure passwords, e.g.,abc123?
Also no.
Providing a means of verifying the validity of user input is the basis for the challenged to follow.
There are three validator modules to implement, each with a single function for you to implement; validate(input). Each of the validators should construct and return a simple Object that describes the nature of the input's validity.
Take a look at Mozilla Developer page Working with Objects for help understanding objects.
One simple way to construct an Object in JavaScript is to just use brackets when initializing a variable.
// A user or person Object...
const creatorOfJavaSCript = {
firstName: "Brendan",
lastName: "Eich"
}
// A film?
const odyssey = {
title: "2001: A Space Odyssey",
imdb: "https://www.imdb.com/title/tt0062622"
}Each validator's validate function as documentation describing what makes input valid or invalid. Be sure to read each method doc carefully!
Each validate implementation should return an error Object to the following specification:
- If the function parameter
inputis considered valid per the requirements described in the code documentation, thevalidatemethod should return an emptyObject - If
inputis invalid, the errorObjectreturned should contain a single attribute named according to the thing the validator is validating (e.g.,email,password,phoneNumber).
For example, if the validate email-validator.js function is called with an input that does not have an @ in it, the Object returned should contain an attribute email with a message specific to the reason why it is invalid. Again, please read the documentation in each validator module carefully.
None of the validator modules have a command line runner. Just code, run the tests, and repeat until they all pass.
The validate(input) method in phone-number-validator.js should return an object with an error message if the input parameter is not valid North American phone number.
Similar to the prior challenges, you can run your tests as follows
npm test -- phone-number-validator.test.jsSimilar to the phone number validator, email-validator.js will be checking the input parameter for some (not all!) of the basic bits and pieces that make up a valid email address.
npm test -- email-validator.test.jsAnd... yeah, you may have picked up on the pattern here – password-validator.js will be have the exact same way as the email or phone number validators, but will check against the password validity criteria defined in this module's documentation.
npm test -- password-validator.test.js