JavaScript - At a glance

Imran Fakhrul — Sat, 19 Oct 2019 06:37:49 +0000

When I started learning JavaScript, I was kind of perplexed, where should I start, what should I learn first, how many concepts does JavaScript really have? Though there were a lot of articles answering those questions, I think they are a bit verbose. And I found a little hard to find the concrete key points from there. So I made a simple note which a beginner may follow and kept it concise so that one can easily extract the key points or terminologies and start researching right away.

Creation history

Creator - Brendan Eich
Created at - 1995
Original name - LiveScript
Renamed - JavaScript

First release

1996 with Netscape

Version history

1st : 1996
2nd : 1998
3rd : 1999
4th : Abandoned
5th : 2009
6th : 2015

Host environments

Web Browser
Adobe Acrobat
Adobe Photoshop
SVG images
Yahoo's Widget engine
Node.js
CouchDB
GNOME

Language type

Multi-paradigm
Dynamic
OOP
Object prototypes
Functional programming

Types

Number
String
Boolean
Object
- Function
- Array
Symbol
null
undefined

Variable

Declaration
- var, let, const

Operators

Assignment (=)
Addition/Concatenation (+)
Substraction (-)
Multiplication (*)
Division (/)
Modulus (%)
Increment (++)
Decrement (--)
Comparison (>, <, <=, >=)
Equality/Not equality (===, ==, !==, !=)
And (&&)
Or (||)
Bitwise

Control structures

if/else
switch
for
while
do-while
for-in
for-of

Truthy and Falsy

Falsy
- false, 0, '', NaN, null, undefined
Truthy
- Everything else which are not falsy, are Truthy

Built in objects

Math
Error
RegEx
Date
Object
String
Number
Array
Boolean
JSON
Promise

Number

Most used APIs
- Number.toString()
- Number.parseInt()
- Number.parseFloat()
- Number.isNaN()
- Number.isFinite()
- Number.isInteger()
- Number.toExponential()
- Number.toFixed()

String

Most used APIs
- String.prototype.length
- String.prototype.charAt()
- String.prototype.fromCharCode()
- String.prototype.concat()
- String.prototype.repeat()
- String.prototype.search()
- String.prototype.indexOf()
- String.prototype.lastIndexOf()
- String.prototype.replace()
- String.prototype.fromCharCode()
- String.prototype.toLowerCase()
- String.prototype.toUpperCase()
- String.prototype.substring()

Object

Most used APIs
- Object.assign()
- Object.create()
- Object.defineProperty()
- Object.defineProperties()
- Object.entries()
- Object.freeze()
- Object.hasOwnProperty()
- Object.isPrototypeOf()
- Object.assign()
- Object.keys()
- Object.getPrototypeOf()
- Object.getOwnPropertyNames()
- Object.getOwnPropertyDescriptor()
- Object.getOwnPropertyDescriptors()

Function

Most used APIs
- Function.name
- Function.prototype
- Function.call()
- Function.bind()
- Function.apply()

Array

Most used APIs
- Array.length
- Array.isArray()
- Array.prototype.pop()
- Array.prototype.push()
- Array.prototype.shift()
- Array.prototype.map()
- Array.prototype.filter()
- Array.prototype.reduce()
- Array.prototype.concat()
- Array.prototype.join()
- Array.prototype.include()
- Array.prototype.splice()
- Array.prototype.forEach()
- Array.prototype.indexOf()
- Array.prototype.find()
- Array.prototype.findIndex()
- Array.prototype.slice()

Those are not all concepts JavaScript has. Those are basics and you can follow them while starting with it rather than roaming here and there aimlessly. There is a lot of stuff inside there. But if you go through the above stuff and keep digging, you may understand yourself what more inside there what should study next.
For deep dive - https://developer.mozilla.org/en-US/docs/Web/JavaScript

DEV Community: Imran Fakhrul