Lecture 203:- Objects

An object is a data structure that stores data and behaviors as key-value pairs. Objects in JavaScript are similar to objects in real life, in the sense that they are made up of properties (the object's attributes) and methods (the object's behaviors).

In JavaScript, an object is created using curly braces {} with key-value pairs separated by commas ,. For example:

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let person = {  name: "John",  age: 25,  sayHello: function() {    console.log("Hello!");  } };

This creates an object person with three properties: name, age, and sayHello. The name and age properties are simple values (strings and numbers, respectively), while the sayHello property is a function.

You can access the properties and methods of an object using dot notation objectName.propertyName or bracket notation objectName["propertyName"]. For example:

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console.log(person.name); // Output: John console.log(person["age"]); // Output: 25 person.sayHello(); // Output: Hello!

You can also add or modify properties and methods of an object using the same dot or bracket notation. For example:

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person.job = "Developer"; person["isMarried"] = false; console.log(person.job); // Output: Developer console.log(person["isMarried"]); // Output: false

You can also delete properties of an object using the delete keyword. For example:

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delete person.job; console.log(person.job); // Output: undefined

Finally, you can loop through the properties and methods of an object using a for...in loop. For example:

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for (let key in person) {  console.log(key + ": " + person[key]); }

This will output:

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name: John age: 25 sayHello: function() {    console.log("Hello!");  } isMarried: false