Learn Javascript: Chapter 1

Learn to Code with Javascript by Darren Jones

Chapter 1: Press Start

• Coding allows one to build apps, hack devices, and write games.
• Chapter topics include programming, algorithms, pseudocode, Javascript, web browsers, and programmer mindsets.
• Programming instructs computers using a language understood by both computers and humans.

Algorithms

• An algorithm is a step-by-step method, originating from Persian mathematician Al-Khwarizmi's algebraic textbook.
• An algorithm should state what to do at each step and what each step accomplishes

Pseudocode

• Pseudocode illustrates a program without language-specific complexities but with general programming conventions.
• Pseudocode is useful for planning a program and idea-sharing.

Brief History Of Programming

• Early computers used punch cards and a binary number system.
• Machine and assembly languages are low-level, tied closely to computer hardware.
• High-level languages like Swift, C#, and Java are compiled and faster.
• Scripting languages like Python, Ruby, and Javascript are interpreted at runtime and often slower.

Javascript

• Javascript is the language of the web, working in almost every browser
• Javascript is interpreted and compiled at runtime - requires an engine to run
• Javascript elements can change while running, making it a dynamic language
• Brendan Eich developed Mocha (prototype Javascript) which Netscape then rebranded Javascript
• Initially used for pop-up ads, Javascript usage then expanded to include internet web applications
• Javascript made its debut in 1995
• ECMAScript standardized Javascript in 1996 to avoid infringing on the "Java" trademark
• Javascript must maintain backward compatibility, allowing old code to function correctly in newer engines

The Console

• The console is a command prompt to run code for testing.
• Online consoles such as https://jsconsole.com are availabl
• Browser consoles can be opened using browser specific keyboard strokes.
• Shift + Ctrl + J (or Option + ⌘ + J) on windows or the F12 key

Web Page Structure

• HTML marks up content, CSS dictates the page look, and JavaScript adds interactivity to make the page functional
• Codepen is useful for using HTML, CSS, and Javascript using three different sections.
• Can be accessed by clicking the console tab

Programmers Mindset

• Computer programs do what it is supposed to do, the programming should also be important. Code should be clear, concise, up to code, and consistent
• Important refactor as code should be effective and easier to make it more efficient and easier to follow
• Important to implement the DRY rule. "Do Not Repeat Yourself"
• A good programmer will always be looking to write code so that the job is done in an efficient way, with as little bugs as possible, and easier to maintain.
• Writing a code is developed over time and involves a lot of problem solving, and getting stuck.
• There should be a good balance of good plans and commented code to help make the program easier to follow

Summary for Chapter 1 "Press Start"

• Algorithms are a set of steps to completing a task.
• Pseudocode can be used to write programs.
• Javascript was created in 1995 and is considered the language of the Web.
• Javascripts main setting is in a browser, but can exist in others.
• Javascript has to have backward compatibility with versions of code
• Code should be readable and refactor if not

Chapter 2: Programming Basics

• Learning how comments work, your programming grammar, datatypes, varibles, and alert boxes

Comments

• Help explain the purpose and rational of the code.
• Single lined comments start with "//" and finish at the end of the line
• Multi-line comments start with "/" and finish with "/"
• The comments should useful and not describe the obvious
• Comments are useful to remind your future self of what the code does

Programming Grammar

• A program is made up of a series of "statements"
• "store response to 'Please enter your name.' as name" is an example.
• Ending with a semicolon might not always be necessary when its on a separate line, but encouraged for best practice.
• A "block" is a series of statements collected together and signified by curly braces.
• Whitespace, such as spaces, tabs, and and new lines sperate different parts of the code. Javascript allows for as much as you want
• Examples of blocks incluse indents for nested code, and multiple lined code.

Data Types

• Every value has a "type" describing the data that contains
• Primitive data types are implemented at the lowest level of programming language and cannot be changed.
• Character/char, String, Integer, Float, and Boolean (true or false) are common primitive data types
• symbol, bigint, and undefined are also values.
• composite data types are made up primititive data types in a structured format ex. arrays and objects

Chapter 3: Letters and Words

Chars and Strings

• A char is singe character and strings are a collection of characters. Javascript uses Strings to represent both.
• A String literal is a literal representation of strings in code, using "" or ''.
• Double quotes are useful in apostrophes
• To escape quotation marks, placing backslash
• Use \n for end of line, \r for return, \t for tab

Find The Char

• A particular character can be found in a String by using charAt() with dot notation.
• Dot notation involves writing a dot followed by your specified method.
• Computers start counting at zero.
• There's a shortcut notation for calling individual parts of a String through [].

Finding Chars

• Can you indexOf() to return and show where and position of the first occurance of of certain substrings.
• If the character doesnt exsist it'll return -1
• LastIndexOf() can be used instead, and shows the character the last appeared at.
• Include() also can be used to return a boolean value.
• StartsWith() can see if a string sarts with a certain character. Also can use endsWith which is the similar.

How Long is a String?

• Every string has a length property, can be accessed through dot notation
• You can also assign a string property

String Arithemtic

• You can do arithmetic to make a longer string
• Combine 2 strings is know as string concatentation
• Important know concatentation doesnt insert spaces for you.
• You can use the concat() method instead to concatenate two methods

Finding the last character in a string

• There are times will will want to know what the last character of a astring is
• Easy enougb if you know what the string is
• Also if you don't you will also not know the value
• Thankfully can use length property to find last character of a string

Whats In a Name?

• Create code and ask for user for their name
• then use what we know to find out their information
• Example using the string "JAVASCRIPT" to print to console

Changing Cases

• is possible to change the case of a strng to uppercase or lowercase letters
• using functions
• The command, these function changes, don't change it will only display the value.

Trimming Space

• trim() function can be used to remove any space from the end of string

More Methods

• Template literals allow use to both types of quote marks in single string and backticks allows multilined code
• interpolation is used with javasctipt

Chapter 4: Template Literals

• Numbers can't use all the same methods with Strings

Integers and Floats

• Classified as a numerical typpe of value
• Numbers can be intigers (whole nummers) such as 3,4,0
• Number can be FloatingPoint numbers(fractions)

How Old

• To apply it all the techniques
• You have a form to write name and age in there. Then applys some Javascript.

Math

• To work with numbers. You will have to know math which is a must know for programming if you want to create games and calculators.
• Has properties and dot notation

Chapter 5: Collections

• Arrays are an order lis of values for example grocery list

Arrays are Javascript

• Is easier than strings but Javascript just wants to do javascript. Code is easier and more accessible
• Is in array Literatl which does use values separated by commeas
• Can get javascript by using name and bracket

Finding The Length of an Array

• Everyr array as an property, You can't touch, but the value should be in there.

Popping and Pushing

• Arratys have methods called pop or push - adding them to or taking them up.
• "Pop" pulls the last item in the array. To see it in action. Can creat and set up const my string so the dot method is easier.

Spreading Strings

• Can look like an empty aray, where they are all ready there to use, without having to type out.

List/Array iterations

• Foreach() method, goes in for every item
• A map() mothod, uses a callback or function. Array to tell you waht to do

Chapter 6

• There are some types to javascript

Booleans

• True or false data and all about logic
• "Al" which there ar