This is my basic JS starting point. This page gives a general overview of JS and links to relevant topics to study further if needed.
Introduction
JavaScript (JS) is a high-level, versatile programming language that is a core technology of the World Wide Web, alongside HTML and CSS. It is essential for creating interactive and dynamic user experiences on websites. Initially developed to make web pages interactive, it has since grown into a language used for full-scale web applications, server-side development, and even mobile app development.
Working within a browser
For chrome, use developer tools -> sources. Then within submenu select Snippets. It will show index.js on the left where we can add JS scripts to see how it affects browser behavior. Then press ⌘+Enter to run.
Quick Overview
The notes don’t go into too much details considering some existing programming knowledge. Maybe at different points it will be compared to existing knowledge (mainly Python). JavaScript is also dynamically typed, with similar data structures. One key difference between them is Python is Object-Oriented while JS is Prototype based.
Here is the primitive data types - which are also inherently immutable. A lot of them have their own methods too.
- String
- Number - technically int and float considered same type here
- Boolean - true or false
- Undefined - value not assigned yet
- Null - absence of value altogether
Check datatype using the function typeof() (built-in)
var - is a keyword used to declare variables
Declaration done using =, comparison done using both == and === . Check Comparison Operators to clarify the differences.
parseInt() converts a string-number into an integer.
.find() to find something based on the callback function. Returns the first match.
.filter() to filter something based on the callback function. Returns an array with all the matches.
.slice() method
.findIndex() method
? for if statements
delete or splice from array
Both i++ as well as i+= is allowed in Javascript.
return works the same as Python.
Use// for inline comment and /* shizle goes here */ for comment snippet
Check Functions for overview and syntax for functions. Check Control Flow for notes on loops and conditionals. Multiple conditionals are combined using && for AND and || for OR.
alert (message) - brings up a pop up with the message prompt (message) - brings up a pop up with message that can take an input
Compilation
JS is neither interpreted nor compiled but uses a mix of both known as just-in-time (Just-In-Time) compiled language.
Move to 1 - JavaScript in HTML basics to have a gentle intro in context of JS as a script.