➢ Ten Functions

"Ten Functions" is a prepared environment for practicing introductory function writing with automated tests for feedback.

Setup Instructions

• If you want more practice working with Git and Github, fork this project on GitHub and then clone your fork to your development box, so you have both your own local copy and a remote in GitHub where you can push your solutions.
• Go here https://glitch.com/edit/#!/remix/ten-functions if you only want to focus on the problems and side-step the git process.

Getting Started

0. Setup your own copy of the code using the instructions above
1. Read the exercise prompts listed below
2. Define your functions that solve the prompts inside of solutions.js.
3. Use feedback to improve responses
4. Submit issues and patches to the Ten Functions project

The "Ten Functions" Exercises 👟

0. The comments to the right of the function call example demonstrate the output of the function's operation on the provided input(s). Add your function definitions to solutions.js. Refresh results.html to run automated tests for feedback on your solutions.

1. Define a function named isTrue that takes in any input and returns true if the input provided is exactly equal to true in value and data type.

    isTrue(true)             // true
    isTrue(false)            // false
    isTrue(0)                // false
    isTrue(null)             // false
    isTrue("true")           // false
    isTrue("Banana")         // false
    isTrue([1, 2])           // false
   

2. Define a function named isFalse that takes in a value and returns a true if and only if the provided input is equal to false in both type and value.

    isFalse(false)             // true
    isFalse(true)              // false
    isFalse(0)                 // false
    isFalse(null)              // false
    isFalse("")                // false
    isFalse("Banana")          // false
    isFalse([1, 2])            // false
   

3. Define a function named not that takes in any input and returns the boolean opposite of the provided input.

    not(false)                  // true
    not(0)                      // true
    not("")                     // true
    not(null)                   // true
    not(NaN)                    // true
    not(undefined)              // true
    not(true)                   // false
    not("something")            // false
    not(Infinity)               // false
    not(123)                    // false
   

4. Define a function named addOne that takes in a single input. If the input is a number or a numeric string, return the value plus one.

    addOne(0)                    // 1
    addOne(2)                    // 3
    addOne(-5)                   // -4 
    addOne(5.789)                // 6.789
    addOne(Infinity)             // Infinity
    addOne("2")                  // 3
    addOne("0")                  // 1
    addOne("banana")             // NaN
    addOne(true)                 // NaN
    addOne(NaN)                  // NaN
   

5. Define a function named isEven that takes in a single input. If the input is an even number or a string containing an even number, return true. Any other input should return false for the output.

    isEven(2)                   // true
    isEven(-8)                  // true
    isEven(0)                   // true
    isEven("42")                // true
    isEven(1)                   // false
    isEven("-3")                // false
    isEven(false)               // false
    isEven("banana")            // false
   

6. Define a function named isIdentical that takes in two input arguments. If each input is equal both in data type and in value, then return true. If the values are not the same data type or not the same value, return false.

    isIdentical(3, 3)                     // true
    isIdentical(false, false)             // true
    isIdentical("hello", "hello")         // true
    isIdentical(3, 3.0)                   // true
    isIdentical(undefined, undefined)     // true
    isIdentical(2, "2")                   // false
    isIdentical("javascript", "java")     // false
   

7. Define a function named isEqual that takes in two input arguments. If each argument is equal only in value, then return true. Otherwise return false.

    isEqual(3, "3")                       // true
    isEqual("abc123", "abc123")           // true
    isEqual(true, 1)                      // true
    isEqual(0, false)                     // true
    isEqual(4, -5)                        // false
    isEqual("java", "javascript")         // false
   

8. Define a function named or that takes in two input arguments. The output returned should be the result of an or operation on both inputs.

    or(true, true)                    // true
    or(true, false)                   // true
    or(false, true)                   // true
    or(false, false)                  // false
    or("hello", "world")              // "hello" (this behavior is non-obvious, research more!)
   

9. Define a function named and that takes in two input arguments and returns the result of a logical and operation of both inputs.

    and(true, true)                    // true
    and(true, false)                   // false
    and(false, true)                   // false
    and(false, false)                  // false
    and("hello", "world")              // "world" (this behavior is non-obvious, research more)
   

10. Define a function named concat that takes in two input arguments. If both arguments are strings, then return the concatenated result. If two numbers are provided, then return the string concatenation of each set of numerals.

    concat("code", "up")                // "codeup"
    concat("connect", 4)                // "connect4"
    concat("hello", "world")            // "helloworld"
    concat(4, 2)                        // "42"
    concat(true, true)                  // "truetrue"
    

Files in this project

• index.html is the welcome page
• results.html shows the ouptut from automated test data
• solutions.js is where you will write your function definitions that solve the exercises below
• tests.js is the suite of automated tests that call your functions in solutions.js with different inputs.

Hints

Consider this example problem.

Write a function called isBoolean that takes in a value and returns a boolean if the argument provided is a boolean value or not.

• isBoolean("Dog") should return false because a string is not a boolean

• isBoolean(false) should return true because only true and false are boolean values.

• When a problem says return, it means return, not console.log.

• When a problem says that a function will take in an input, then it means the function must be defined so that it takes in an argument as its input, rather than relying on variables defined outside the function.

The following example is incorrect because the function does not take in an argument. It's modifying a global variable, and that is not the same as accepting an input as an argument.

var input = "Grace Hopper"
function isBoolean() {
    return typeof input == "boolean";
}

This is incorrect because the function doesn't return the output. Functions that do not have an explicit return statement return undefined by default.

function isBoolean(input) {
    console.log(typeof input == 'boolean');
}

Correct solution:

function isBoolean(input) {
    return typeof input == "boolean";
}

About

• Proudly hosted and edited on Glitch! 🎏
• Testing framework: Jasmine
• Made by Ryan Orsinger

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