Add Web APIs section with examples (#213)

* Add Web APIs section with examples

* Update web-apis.md

* Update web-apis.md

* Corrected markdown syntax and added more context to Fetch API section

* Update web-apis.md

fix merge conflicts

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Co-authored-by: Suman Kunwar <[email protected]>

Author: srishti-coder

web-apis.md

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+# Web APIs
+
+Web APIs are interfaces provided by the browser that allow you to interact with the browser and the underlying operating system.
+
+Some common Web APIs include:
+
+- **DOM API**: Allows for dynamic manipulation of HTML and CSS.
+- **Fetch API**: Enables network requests to retrieve resources from servers.
+- **Geolocation API**: Provides the user's location.
+- **Canvas API**: Used for drawing graphics via JavaScript.
+- **Storage API**: Allows for storing data on the client-side.
+
+### Why Use Web APIs?
+
+Web APIs are essential for modern web development because they:
+- **Enable Rich User Experiences**: They allow developers to create interactive and dynamic web applications.
+- **Provide Access to Browser Capabilities**: Web APIs offer access to features like geolocation, notifications, and local storage.
+- **Facilitate Communication with Servers**: They make it easy to fetch data from servers, submit forms, and interact with web services.
+
+### How Web APIs Work?
+
+Web APIs work by providing a set of functions and properties that developers can use to interact with the browser. These functions are exposed by the browser and can be called using JavaScript. When a function is called, the browser performs the corresponding action, such as fetching data from a server or updating the DOM.
+
+#### Example Workflow
+
+1.User Action: The user interacts with the web application, such as clicking a button.
+
+2.API Call: JavaScript code in the web application makes a call to a Web API.
+
+3.Browser Action: The browser performs the requested action, such as retrieving data or updating the display.
+
+4.Response Handling: The web application handles the response from the API and updates the user interface accordingly.
+
+
+## DOM Manipulation
+
+The Document Object Model (DOM) is a programming interface for web documents. It represents the page so that programs can change the document structure, style, and content.
+
+### Example Code: Changing the Content of an Element
+
+
+```javascript
+document.getElementById("demo").innerHTML = "Hello, World!";
+```
+		
+## Fetch API 
+
+
+The Fetch API provides an interface for fetching resources (including across the network).
+
+### Example Code: Simple Fetch Request
+
+
+```javascript
+fetch('https://api.example.com/data')
+  .then(response => response.json())
+  .then(data => console.log(data))
+  .catch(error => console.error('Error:'));
+```
+
+## Geolocation API
+
+The Geolocation API allows the user to provide their location to web applications if they so desire. For privacy reasons, the user is asked for permission to report location information.
+
+### Example Code: Getting User Location
+
+```javascript
+if ("geolocation" in navigator) {
+  navigator.geolocation.getCurrentPosition(function(position) {
+    console.log("Latitude: " + position.coords.latitude);
+    console.log("Longitude: " + position.coords.longitude);
+  });
+} else {
+  console.log("Geolocation is not supported by this browser.");
+}
+```
+## Canvas API
+
+The Canvas API provides a means for drawing graphics via JavaScript and the HTML <canvas> element.
+
+###Example Code: Drawing Shapes on Canvas
+
+```javascript
+let canvas = document.getElementById('myCanvas');
+let context = canvas.getContext('2d');
+
+// Draw a rectangle
+context.fillStyle = '#FF0000';
+context.fillRect(10, 10, 150, 100);
+```
+
+## Storage API
+
+The Web Storage API provides mechanisms by which browsers can store key-value pairs, in a much more intuitive fashion than using cookies.
+
+### Example Code: Storing Data in localStorage
+
+
+#### Local stoage
+```javascript
+// Save data to local storage
+localStorage.setItem('key', 'value');
+
+// Retrieve data from local storage
+let value = localStorage.getItem('key');
+console.log(value);
+```
+#### Session Storage
+
+```javascript
+// Save data to session storage
+sessionStorage.setItem('key', 'value');
+
+// Retrieve data from session storage
+let value = sessionStorage.getItem('key');
+console.log(value);
+```
+
+## Notification API
+
+The Notification API allows web pages to control the display of system notifications to the end user.
+
+### Example Code: Displaying a Notification
+
+```javascript
+
+if (Notification.permission === "granted") {
+  new Notification("Hello, World!");
+} else if (Notification.permission !== "denied") {
+  Notification.requestPermission().then(permission => {
+    if (permission === "granted") {
+      new Notification("Hello, World!");
+    }
+  });
+}
+```