Dr. Derek Austin DoctorDerek

## History\-1033eb3b\entries.json
{"version":1,"resource":"file:///c%3A/dev/learn-penguin/pages/level/%5Bworld%5D/%5Bid%5D.page.tsx","entries":[{"id":"9tdt.tsx","timestamp":1653504720885},{"id":"jDGs.tsx","timestamp":1653504732111},{"id":"MBQa.tsx","timestamp":1653504747566},{"id":"GQjv.tsx","timestamp":1653504823082},{"id":"Lw3z.tsx","source":"undoRedo.source","timestamp":1653504827867},{"id":"r3mT.tsx","timestamp":1653504833056},{"id":"j0mh.tsx","source":"undoRedo.source","timestamp":1653504838631},{"id":"FV1x.tsx","timestamp":1653504845182},{"id":"NSBn.tsx","timestamp":1653504958300},{"id":"eXJ4.tsx","timestamp":1653504987900},{"id":"cQZy.tsx","source":"Workspace Edit","timestamp":1653516573565},{"id":"XC0w.tsx","timestamp":1653516595199},{"id":"5sZe.tsx","source":"Workspace Edit","timestamp":1653516620077},{"id":"Ndpg.tsx","timestamp":1653516622869},{"id":"QXsn.tsx","timestamp":1653516925743},{"id":"8BEe.tsx","timestamp":1653516937811},{"id":"w2EA.tsx","timestamp":1653516961799},{"id":"vkkV.tsx","timestamp":1653517188004},{"id":"gvlE.tsx"

## What Is The Short-Circuit Operator in JavaScript && (Logical AND) 1.js
// Using && will prevent nonsense code from being executed.
false && console.log(NoNsEnSe_CoDE) // nothing happens

// You'll frequently see && used for type-checking.
const bananas = "🍌🍌🍌🍌🍌"
typeof bananas === "string" && console.log(bananas) // 🍌🍌🍌🍌🍌

// For example, you might be expecting an array, not a string.
Array.isArray(bananas) && bananas.push("🍌") // nothing happens

## A Better Method of Type Checking JavaScript Objects - Object.getPrototypeOf().js
// The typeof null is "object" in JavaScript.
console.log(typeof null === "object") // true

// Let's look at type checking a Date object.
const date = new Date()
console.log(typeof date) // "object"
console.log(Object.prototype.toString.call(date)) // [object Date]
console.log(date.constructor) // function Date()
console.log(date.constructor.name) // "Date"
console.log(date instanceof Date) // true

## What Is The Short-Circuit Operator in JavaScript && (Logical AND) 2.js
// && can be used to prevent errors, because the error won't be thrown.
const nullBanana = null
try {
  console.log(nullBanana.length)
} catch (e) {
  console.log(e)
}
// Output: "TypeError: null has no properties."

// Using && short-circuits the code, so the TypeError doesn't occur.

## How to Check for an Object (Javascript Object Null Check).js
const object = { "🔑key🔑": "💸value💸" }
console.log(typeof object) // "object"
console.log(object !== null) // true
console.log(object != null) // true

console.log(typeof null) // "object"
console.log(null !== null) // false
console.log(null != null) // false

console.log(typeof undefined) // "undefined"
	// Using && will prevent nonsense code from being executed.
	false && console.log(NoNsEnSe_CoDE) // nothing happens

	// You'll frequently see && used for type-checking.
	const bananas = "🍌🍌🍌🍌🍌"
	typeof bananas === "string" && console.log(bananas) // 🍌🍌🍌🍌🍌

	// For example, you might be expecting an array, not a string.
	Array.isArray(bananas) && bananas.push("🍌") // nothing happens
	// The typeof null is "object" in JavaScript.
	console.log(typeof null === "object") // true

	// Let's look at type checking a Date object.
	const date = new Date()
	console.log(typeof date) // "object"
	console.log(Object.prototype.toString.call(date)) // [object Date]
	console.log(date.constructor) // function Date()
	console.log(date.constructor.name) // "Date"
	console.log(date instanceof Date) // true
	// && can be used to prevent errors, because the error won't be thrown.
	const nullBanana = null
	try {
	console.log(nullBanana.length)
	} catch (e) {
	console.log(e)
	}
	// Output: "TypeError: null has no properties."

	// Using && short-circuits the code, so the TypeError doesn't occur.
	const object = { "🔑key🔑": "💸value💸" }
	console.log(typeof object) // "object"
	console.log(object !== null) // true
	console.log(object != null) // true

	console.log(typeof null) // "object"
	console.log(null !== null) // false
	console.log(null != null) // false

	console.log(typeof undefined) // "undefined"