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Code 102, Intro to Software Development
Class 06 - Reading Notes
Dynamic web pages with JavaScript
JavaScript
Summarized from MDN Web Docs
JavaScript is a lightweight, interpreted, compiled programming language with first-class functions. While it is most well-known as the scripting language for Web pages, many non-browser environments also use it, such as Node.js, Apache CouchDB, and Adobe Acrobat. Java is a very different programming language.
JavaScript Variables
Variables are “containers for storing data”, and are declared in four ways:
var
let
const
using nothing
For older browsers, the var option should be used.
Keywords let and const were added to JS in 2015.
For general rules, use const. If the variable can change, use let.
Example:
const price1 = 5;
const price2 = 6;
let total = price1 + price2;
JavaScript Identifiers
All variables bust be identified with unique names called identifiers.
Some general rules for variable names:
Names can contain letters, digits, underscores, and dollar signs.
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Names must begin with a letter
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Names can also begin with $ and _
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Names are case sensitive (y and Y are different variables)
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Reserved words (like JavaScript keywords) cannot be used as names
For more rules on variables, visit W3Schools
How Computers Really Work
How Computers Really Work Playlist
All computers perform four basic functions:
Input, Storage, Processing, Output
Input is what we physically do with the device. The information that is given to the computer.
Storage and Processing take that information, and manipulate it with algorithms, saving what is necessary and sending information to the output device(S).
Output is the information we receive from the computer in the form of display, sound, movement, and more.
Computers take in, process, store, and output information using thousands of small wires with ‘on’ and ‘off’ signals. These signals are interpreted as *binary*. All input information is translated by the computer into numbers, which are then represented as binary code, and processed into visual, sound, video, and movement outputs. Everthing is based on numbers!
https://chrisjohnston1986.github.io/reading-notes/102class06reading