CodeHS Unit 3 Programming With JavaScript

Code

A way to conveying info as symbols

Code is just ______ that have meaning when read in a _______ way

symbols, predefined

Program/Software

Computer-readable code

Types of code (5)

color code

genetic code

morse code

natural language

computer program

In order for us to give computers instructions, we need to to provide instructions in a __________ ___________.

programming language

Each key and mouse click generates a unique _______ (input) that gets sent to the computer. A program then processes the _______ to figure out what to do with them. The program then outputs more ________ that tell the computer to do certain things.

number(s)

All numbers sent as inputs and output to and from a computer are represented using ____ and _____.

0s and 1s

A special program called the compiler takes care of converting our _________ into the ...

program, binary machine code

At a high level, computer programs really just implement ___________

algorithms

Algorithm

A self-contained, step by step set of instructions to solve a problem

_________ implement algorithms

programs

Programs put algorithms into a _______ _________ form

computer executable

How to print "Hello World"

A ________ is like a box that can hold a value

variable

Declaring a variable

(does not enter a value into the variable)

Initializing a variable

Declares a variable and sets its initial value

Assigning to a variable

Changing a variable's value

Types of Variables

Number

Boolean

String

Numeric Variables - Integers

Whole numbers

Numeric Variables - Floats

Real numbers (can be decimals)

Boolean Variables

true/false

String Variable

Text (goes between quotes)

Variable names start with... (3)

a letter

$

_

Variables Example

Functions used to receive user inputs

Use readLine to get/read ... from the user

strings of text

Use readInt to get/read ____ from the user

integers

Use readFLoat to get/read ____ from the user

floats (real numbers)

User input Example

Arithmetic Operators in JavaScript

When a modulus operator is used, it...

divides the two numbers and takes the remainder

Math in JavaScript Example #1

Shortcut for adding and subtracting 1 from a variable

How is the coordinate system oriented for the programming canvas?

The function ____________ gets the width of the canvas

getWidth()

The function ____________ gets the height of the canvas

getHeight()

How to make text located at a certain location

How to make a circle centered at a certain location

How to make a rectangle located at a certain location

When setting the position of rectangles, the position is set at the ________________ of the graphic

top left corner

When setting the position of text, the position is set at the ________________ of the graphic

bottom left corner

Graphics example (8 ball)

Mouse event

When the user does something with the mouse, like clicking or moving

To respond to a mouse click, we use _______ functions

callback

Callback function

A function passed as a parameter to another function in order to be called later. (drawCircle)

When the mouse is clicked, whatever function was passed to ____________ is called

mouseClickMethod

e is an __________ ___________ and can be any variable. We may sometimes use the variable ____________

input parameter, event

e stores information about ...

a mouse/key event

To get the x ant y positions of a click, use...

Click to add a circle example

Key Event Functions

Functions to detect which key is pressed

Moving graphic with keys

What is the proper function to call to print to the screen?

println

What keyword do you need to use to define a variable in JavaScript?

var

What function do you need to call to ask the user of the program to enter text?

readLine

To ask the user of the program for a number, which function should you use?

Both readInt and readFloat are for numbers.

Question in image

What is your name? Karel

Hello Karel

Question in image

Welcome! ‎¡Hola! ‎¡Hola! Bonjour!

Question in image

Enter a character. P

: c P

What will the following code print to the screen?

println(2 + 2);

4

What symbol do you use to do division in JavaScript?

/

What symbol do you use to do multiplication in JavaScript?

*

29

4

10

2

Suppose we've written a function drawCircle that we want to call every time the mouse is clicked. How can we do this?

mouseClickMethod(drawCircle);

function start(){

keyDownMethod(animate);

}

Why are computer programs an example of code?

Computer programs are an example of code because programmers use the different programming languages as predefined symbols to communicate with a computer.

Interactive

allowing the flow of information both ways between a computer and its user (with inputs and outputs)

Why is it important for computer programs to display information to users?

It is important for computer programs to display information to users so that the users are aware of the effects of their inputs and the status of either themselves or the computer. For example, it is important for there to be an error message when a user logs in incorrectly so that the user knows that they are not able to gain access because their username/password is wrong.

Why might variables be useful in our programs?

Variables might be useful in our programs to store certain values and allow the values to be easily referenced/recalled later in the program using the variable names

Why is it useful for programs to be able to accept user input?

It is useful for programs to be able to accept user input so the user can both access their personal information/account and so the user can have a personalized experience within the application. For instance, a person enters their login information into a program in order to access their account within the application.

Why is it useful for programs to be able to perform mathematical computations?

It is useful for programs to be able to perform mathematical computations so that the human using the program does not have to waste time calculating the answer themself or lack confidence in the accuracy of their answer since the computer solves the computation much quicker and more accurately. (Math computation programs are especially useful when the math calculation is complex and/or time consuming.)