Javascript Exercise: Conditionals and Data-Types

Instructions

Fork this repository, then clone it onto your system.
Write your solution in script.js. Open index.html in your browser, which will run your code. Use your browser's console to examine any output where necessary.
Complete as many of the following exercises as you can in 40 minutes. Do prioritize the standard exercises over the bonus or extra ones.
When you are done, practise using git by using git add . to stage your changes, then git commit -m 'your message' to commit your changes, and git push to push your changes up to your repo. Next, create and submit a pull request on github.com. That will be the method by which our homework exercises will be submitted.

Exercise 1

Prompt the user for 2 numbers, then console.log their difference. For example, if the user gives the numbers 2 and 3, the result should be 1. If the user gives the numbers 3 and 2, the result should still be 1. Hint: To get the user input and store it in a variable, we can do var someVar = prompt("Give me a high five");. Consider asking for 1 number at a time first.

Exercise 2

Prompt the user for a number, then console.log its ordinal version. For example, if the user inputs 1, the result should be "1st". If the user inputs 10, the result should be "10th". If the user inputs 421, the result should be "421st". Hint: There is a function that can return the character at a specified position in a string. Search Google / MDN for 'javascript string methods' if you need to.

Exercise 3

Generate a random integer (hint: search Google or MDN) between 1 to 10. Prompt the user for an integer between 1 to 10, then let the user know whether his/her number matched the randomly generated one.

Exercise 4

Generate a random string of length 6 alphanumeric characters. E.g. a result might be "a5bxt1". Running it again might give "2bhdr3". Hint: Pseudocode this first, possibly starting from the end result. What information do you need to construct the string? How would you get that information? Can you store fixed information in a convenient place first?

Bonus: Generate a random alphanumeric string of any specified length.

Exercise 5

Shuffle the elements of the given array below. E.g. running your code might produce [4, 1, 16, 8, 128, 2, 32, 64] once, and [128, 1, 2, 64, 16, 4, 8, 32] the next time.

var testArray = [1, 2, 4, 8, 16, 32, 64, 128];

Exercise 6

Examine the phonebook below.

Prompt the user for a name, and show (in any way, e.g. console.log) the phone number corresponding to the given name.
Prompt the user for a name and a number. Update the number corresponding to the name if the name exists in the phonebook.
Prompt the user for a name and a number. If the name and number do not already exist in the phonebook, insert it into the phonebook.
Prompt the user for a name. If the name exists in the phonebook, erase its record.

Bonus: Prompt the user for a number. If the number exists in the phonebook, show the name corresponding to it.

Hint: The phonebook is a JS Object. Search Google / MDN for 'Javascript Object methods' to see if there might be something useful.

var Phonebook = {
    "Jason"         :   91216599,
    "Amelie"        :   64239839,
    "Sing An"       :   85404834,
    "Ong Tng Kai"   :   94547788,
    "Nelson Tan"    :   63396565
};

Bonus Exercise 7

JS Array / Object Handling - References vs Values

A common class of bugs that programmers face occurs when they change an object that they didn't mean to.

Examine the array below. Prompt the user for 2 integers. Swap the elements in the 2 positions of the array corresponding to the user input, and display the result. E.g. if the user enters 3 and 1, then display [3, 2, 1, 4, 5].

Bonus: Do the same, but without changing the below array, i.e. if the user enters 3 and 1, display [3, 2, 1, 4, 5], but console.log(MutateMeNot) should still produce [1, 2, 3, 4, 5].

var MutateMeNot = [1, 2, 3, 4, 5];

jellythewobbly/js-conditionals-data-types