Objects In JavaScript #19 | Complete JavaScript Tutorials | #javascript #webdevelopment

In this video we have discuss about the topic "Objects" In JavaScript In JavaScript, almost "everything" is an object. Booleans can be objects (if defined with the new keyword) Numbers can be objects (if defined with the new keyword) Strings can be objects (if defined with the new keyword) Dates are always objects Maths are always objects Regular expressions are always objects Arrays are always objects Functions are always objects Objects are always objects All JavaScript values, except primitives, are objects. JavaScript Primitives A primitive value is a value that has no properties or methods. 3.14 is a primitive value A primitive data type is data that has a primitive value. JavaScript defines 7 types of primitive data types: Examples string number boolean null undefined symbol bigint Immutable Primitive values are immutable (they are hardcoded and cannot be changed). if x = 3.14, you can change the value of x, but you cannot change the value of 3.14. Value Type Comment "Hello" string "Hello" is always "Hello" 3.14 number 3.14 is always 3.14 true boolean true is always true false boolean false is always false null null (object) null is always null undefined undefined undefined is always undefined Objects are Variables JavaScript variables can contain single values: Example let person = "John Doe"; JavaScript variables can also contain many values. Objects are variables too. But objects can contain many values. Object values are written as name : value pairs (name and value separated by a colon). Example let person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"}; A JavaScript object is a collection of named values It is a common practice to declare objects with the const keyword. Example const person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"}; ADVERTISEMENT Object Properties The named values, in JavaScript objects, are called properties. Property Value firstName John lastName Doe age 50 eyeColor blue Objects written as name value pairs are similar to: Associative arrays in PHP Dictionaries in Python Hash tables in C Hash maps in Java Hashes in Ruby and Perl Object Methods Methods are actions that can be performed on objects. Object properties can be both primitive values, other objects, and functions. An object method is an object property containing a function definition. Property Value firstName John lastName Doe age 50 eyeColor blue fullName function() {return this.firstName + " " + this.lastName;} JavaScript objects are containers for named values, called properties and methods. You will learn more about methods in the next chapters. Creating a JavaScript Object With JavaScript, you can define and create your own objects. There are different ways to create new objects: Create a single object, using an object literal. Create a single object, with the keyword new. Define an object constructor, and then create objects of the constructed type. Create an object using Object.create(). Using an Object Literal This is the easiest way to create a JavaScript Object. Using an object literal, you both define and create an object in one statement. An object literal is a list of name:value pairs (like age:50) inside curly braces {}. The following example creates a new JavaScript object with four properties: Example const person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"}; Spaces and line breaks are not important. An object definition can span multiple lines: Example const person = { firstName: "John", lastName: "Doe", age: 50, eyeColor: "blue" }; This example creates an empty JavaScript object, and then adds 4 properties: Example const person = {}; person.firstName = "John"; person.lastName = "Doe"; person.age = 50; person.eyeColor = "blue"; Using the JavaScript Keyword new The following example create a new JavaScript object using new Object(), and then adds 4 properties: Example const person = new Object(); person.firstName = "John"; person.lastName = "Doe"; person.age = 50; person.eyeColor = "blue"; The examples above do exactly the same. #javascript #coding #webdevelopment #codelife #codeschool #html #css #javascripttutorials #utkarshguptadhruv #webdevelopmenttutorial

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