panpsychism/unit_01/w01d04/homework/js_basics.md

Javascript Basics

Setup

Make a folder called js_basics inside your homework folder. Inside js_basics touch an index.html and an app.js and link them together. Write all of your javascript answers in app.js, and test them in the Chrome console.

Any non-javascript written answers can be made into a comment in your js file by putting a pound # at the beginning of the line. Alternatively, comment out written work by using command + / in sublime. You can select blocks of text and comment them out with this shortcut.

Conceptual Questions

1. How do we assign a value to a variable?
2. How do we change the value of a variable?
3. How do we assign an existing variable to a new variable?
4. How do we use a variable within an expression?

Exercises

1. Create a variable called firstVariable.

• assign it the value of a string => "Hello World"
• change the value of this variable to a number.
• store the value of firstVariable into a new variable called secondVariable
• change the value of secondVariable to a string.
• What is the value of firstVariable?

2. Create a variable called yourName and set it equal to your name as a string.

• Write an expression that takes the string "Hello, my name is " and the variable yourName so that it returns a new string with them concatenated. (ex: "Hello, my name is Jean Valjean")

...

Javascript Primitives

Conceptual Questions

1. Name 4 different built in primitives in Javascript.
2. What is the difference between an integer and a float?
3. How do you create an empty array and store it in a variable?

Exercises

1. Given the following array var a = [1, 10, "Hello", true]

• how do you access the 1st element in the array?
• Change the value of "Hello" to "World".
• Check the value of a to make sure it updated the array.

2. Given the following array ["Meeseeks", "Coldness", "21 Berry", "Venkman"]

   • What would you write to access the 3rd element of the array?
   • Change the value of "Venkman" to "Slimer"
   • Add a new element, "Cloud City" to the array.

3. Create a string that contains quotes and store it in a variable.

4. What is the result from the expression "World" * 5. Why?

JavaScript - Primitive Methods & Properties

Conceptual Questions

1. List at least 5 properties built into a string.
2. List at least 2 method examples built into an array.

Exercises

1. Given the following string "The Peculiar Purple Pieman of Porcupine Peak"

   • How can we check the length of this string?

2. Given the following array [5,10,500,20]

   • using the push method, add the string "Egon" to the end of the array.
   • using a different method, remove the string from the end of the array.
   • using the unshift method, add the string "Bob Marley" to the beginning of the array
   • using a different method, remove the string from the beginning of the array

...

Javascript - operators

Exercises

1.

Using the provided variable definitions, replace the blanks with a mathematical or boolean operator that evaluates the expression to true. 👋

  var a = 4;
  var b = 53;
  var c = 57;
  var d = 16;
  var e = 'Kevin';

• a _ b;
• c _ d;
• 'Name' ___ 'Name';
• a _ b ___ c;
• a _ a ___ d;
• e ___ 'Kevin';
• 48 ___ '48';

...