JavaScript Object Hierarchy Course

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## Introduction
JavaScript follows an object-oriented approach where objects have properties and methods. Understanding the JavaScript object hierarchy helps in efficient coding and debugging.

## Hierarchy of JavaScript Objects
Below is the general hierarchy of JavaScript objects:

Window ├── Document │ ├── Forms │ ├── Images │ ├── Links ├── History ├── Navigator


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## Window Object
The `window` object is the topmost object in the JavaScript hierarchy. It represents the browser window.

### Window Properties
- `defaultStatus`
- `frames`
- `opener`
- `parent`
- `scroll`
- `self`
- `status`
- `top`

### Window Methods
- `alert()`
- `blur()`
- `close()`
- `confirm()`
- `focus()`
- `open()`
- `prompt()`
- `setTimeout()`
- `clearTimeout()`

### Window Event Handlers
- `onLoad`
- `onUnload`
- `onBlur`
- `onFocus`

---

## History Object
The `history` object keeps track of visited pages.

### History Methods
- `length`
- `forward()`
- `go()`
- `back()`

---

## Navigator Object
The `navigator` object provides information about the browser.

### Navigator Properties
- `appCodeName`
- `appName`
- `appVersion`
- `mimeTypes`
- `plugins`
- `userAgent`
- `javaEnabled()`

---

## Document Object
The `document` object represents the HTML page.

### Document Properties
- `alinkColor`
- `anchors`
- `applets`
- `bgColor`
- `cookie`
- `fgColor`
- `forms`
- `images`
- `lastModified`
- `linkColor`
- `links`
- `location`
- `referrer`
- `title`
- `vlinkColor`

### Document Methods
- `clear()`
- `close()`
- `open()`
- `write()`
- `writeln()`

---

## Image Object
An image object allows manipulation of images on a webpage.

### Image Properties
- `border`
- `complete`
- `height`
- `hspace`
- `lowsrc`
- `name`
- `src`
- `vspace`
- `width`

---

## Form Object
The `form` object represents an HTML form.

### Form Properties
- `action`
- `elements`
- `encoding`
- `method`
- `name`
- `target`

### Form Methods
- `submit()`
- `reset()`

### Form Event Handlers
- `onSubmit`
- `onReset`

---

## Text Input Object
A text input object represents an input field.

### Text Input Properties
- `defaultValue`
- `name`
- `type`
- `value`

### Text Input Methods
- `focus()`
- `blur()`
- `select()`

### Text Input Event Handlers
- `onBlur`
- `onChange`
- `onFocus`
- `onSelect`

---

## Built-in Objects

### Array Object
The `Array` object is used to store multiple values.

#### Creating an Array
```javascript
var myCars = new Array("Saab", "Volvo", "BMW");

Accessing Array Elements

document.write(myCars[0]); // Output: Saab

Modifying an Array

myCars[0] = "Opel";

Date Object

The Date object is used to handle dates and times.
Creating a Date Object

var myDate = new Date();

Setting a Specific Date

myDate.setFullYear(2010, 0, 14);

Comparing Dates

var today = new Date();
if (myDate > today) {
  alert("Future Date");
} else {
  alert("Past Date");
}

Math Object

The Math object allows mathematical calculations.
Constants

Math.PI
Math.SQRT2

Methods

Math.round(4.7);  // Output: 5
Math.random();    // Output: Random number between 0 and 1
Math.floor(Math.random() * 10); // Output: Random number between 0 and 10

String Object

The String object is used to manipulate text.
Finding String Length

var txt = "Hello World!";
document.write(txt.length); // Output: 12

Converting to Uppercase

document.write(txt.toUpperCase()); // Output: HELLO WORLD!

Conclusion

This course covered the JavaScript object hierarchy, including key objects like window, document, navigator, and built-in objects like Array, Date, Math, and String. Understanding these objects is crucial for effective JavaScript programming.