The script tag External script file

Semicolon

Comment

Use Strict

Variable and Constant var instead of let Variable Naming Case Sensitive Reserved Words An Assignment without use strict Constant Uppercase Constant

Data Types Number Infinity NaN String Boolean Null Undefined Type of Operator Type Conversions Converting to String Converting to Number Converting to Boolean parseInt() and parseFloat()

Primitive As Object Constructor method for Primitive type Numbers Number.toString Rounding a Number Math.floor() Math.ceil() Math.round() Math.trunc() Math.random() Math.max(a, b, c, ...) Math.min(a, b, c...) Math.pow(n, power) toFixed() Infinity and NaN : isFinite and isNaN Object.is : Strict Equality Check

Special Character : Escape Squence Hexa Code String length Accessing characters charAt() Strings are immutable Changing the case toUpperCase() toLowerCase() Searching for a substring str.indexOf(substr, pos) include() startsWith() | endsWith() Getting a substring str.slice(start [, end]) str.substring(start [, end]) str.substr(start [, length]) UTF-16 Code str.codePointAt(pos) String.fromCodePoint(code)

String Concatenation Unary Plus Assignment Reminder % Exponentiation ** Increment/Decrement Comma Comparasion Operator String Comparasion

Declaration Accessing Elements Replacing Elements Trailing Comma Array can contain any type of Elements length array.push(item) array.pop() array.shift() array.unshift(item) delete toString array.splice() slice() arr.concat() Iteration Array is actually an Object Performance new Array() Iterate: forEach Searching in array indexOf() lastIndexOf() includes() find() findIndex() filter() Transform an array map() sort() reverse() split(delim) join() Array.isArray() Most methods support “thisArg”

Function Declaration Local Variables Outer Variables || Global Variables Parameters Default Values Returning Values Function Expression Callback Function Function Declaration Vs. Function Expression Arrow Function

Object Literals and properties Multiword Property Special property __proto__ Square brackets Computed Property : Variable as a property Property value shorthand Existence check For In Loop Copying By Reference Comparison by reference Const Object Cloning Object : Object.assign Deep Cloning Methods in an Object this Internals: Reference Type Arrow functions have no “this” Object to primitive conversion Symbol.toPrimitive toString/valueOf Constructor Function : new new.target Global Object : Window Use of Window “this” and global object

Symbols Symbols are unique “Hidden” properties Symbols in a literal Symbols are skipped by for…in Global Symbols Symbol.keyFor Get all Symbols : Object.getOwnPropertySymbols() System Symbols

Iterable Symbol.iterator String is Iterable Calling an iterator explicitly Iterables and Array-Likes Array.from

Map map.set(key, value) map.get(key) map.has(key) map.delete(key) map.clear() map.size Map from Object : Object.entries() Iteration over Map map.keys() map.values() map.entries() Set set.add(value) set.delete(value) set.has(value) set.clear() set.size Iteration over Set set.keys() set.values() set.entries() keys(), values() and entries() for Object

Destructing Assignment Array destructuring Looping with .entries() The rest ‘…’ Default Values Object Destructing Test operator with object Without let Nested Destructing Smart function parameters

JSON JSON.stringify() JSON.stringify fails for Circular Reference toJSON() JSON.parse() Using reviver

Recursion Recursive traversals Rest parameters The “arguments” variable Spread operator Merging Array using Spread Operator Spread Operator Works on any Iterator Array.from Vs Spread Operator Closure Lexical Environment Nested functions Environments in detail Lexical Environment for Code blocks and loops, IIFE Garbage collection of Lexical Environment

Function object, NFE func.name Property func.length Property Adding Custom Property Function Closure Vs Function Property Named Function Expression(NFE) Sum with an arbitrary amount of brackets new Function Lexical Environment for new Function

Scheduling : setTimeout and setInterval setTimeout() clearTimeout() setInterval() clearInterval() Modal windows freeze time in Chrome/Opera/Safari Recursive setTimeout Garbage collection : Scheduler setTimeout(…,0) Splitting CPU-hungry tasks Minimal delay of nested timers in-browser Allowing the browser to render

Transparent caching func.call() func.apply() Borrowing a method Function binding

Currying Advanced curry implementation

Arrow Function Arrow functions have no “this” Arrow functions can’t run with new Arrows have no “arguments”

Property Flags Read-only Non-enumerable Non-configurable Object.defineProperties Object.getOwnPropertyDescriptors Object.getOwnPropertyNames

Getters and setters Accessor descriptors Smart Getters and Setters Using for compatibility

[[Prototype]] Data Properties Accessor Properties The value of “this” F.prototype Default F.prototype, constructor property Hiding Properties Native prototypes Other built-in prototypes Native Prototype for Primitive Data Types Changing native prototypes Borrowing from prototypes Methods for prototypes __proto__ as a key Getting all properties Object.getOwnPropertyNames(obj) Object.getOwnPropertySymbols(obj) Reflect.ownKeys(obj)

Class Functional class pattern Factory class pattern Prototype-based classes Prototype-based inheritance for classes Classes Constructors require new Class methods are non-enumerable Getters/setters Class Expression Static methods Prototype Relation

Inheritance Overriding a method super Arrow functions have no super Overriding constructor Super: internals, [[HomeObject]] [[HomeObject]] Static methods and inheritance Natives are extendable Class checking: "instanceof" isPrototypeOf() Symbol.toStringTag

Mixins (Incomplete)

Error Handling Error Object Example Throwing Error Rethrowing try…catch…finally Global catch

Custom Error Extending Error Further inheritance