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Browser APIs

Browser APIs in JavaScript provide functionalities like storing data locally, making HTTP requests, managing browsing history, and accessing device location, enhancing web applications with interactive features and improved user experiences.

Table of Contents

Local Storage

  • Local Storage is a mechanism provided by web browsers that allows web applications to store data locally within the user's browser.
  • It provides a simple key-value storage system where data is persisted even after the browser window is closed or the user navigates away from the page.
  • It's commonly used for storing small amounts of data such as user preferences, session information, or cached data to improve application performance.
  • Data stored in local storage is scoped to the origin (the combination of protocol, domain, and port), meaning data from one origin cannot be accessed by another.
  • To use local storage, you can access the localStorage object in JavaScript.
  • To store data, use localStorage.setItem(key, value).
  • To retrieve data, use localStorage.getItem(key).
  • To remove data, use localStorage.removeItem(key).

Example:

localStorage.setItem('username', 'rajnish')
let username = localStorage.getItem('username')
console.log(username) // Output: rajnish

Fetch API

  • The Fetch API provides an interface for making HTTP requests in the browser, allowing web developers to fetch resources asynchronously from the server.
  • It provides a more powerful and flexible alternative to the older XMLHttpRequest (XHR) API.
  • Fetch API supports promises, making it easier to work with asynchronous code and providing a cleaner syntax compared to callbacks.
  • It supports various features such as streaming responses, sending and receiving JSON data, setting request headers, and handling different types of content.
  • To make an HTTP request using Fetch API, use the fetch() function.
  • Pass the URL of the resource you want to fetch as an argument to fetch().
  • Handle the promise returned by fetch() using .then() and .catch() to process the response or handle errors.

Example:

fetch('https://api.example.com/data')
  .then((response) => response.json())
  .then((data) => console.log(data))
  .catch((error) => console.error('Error:', error))

History API

  • The History API allows developers to interact with the browser's session history, enabling them to manipulate the browser's history stack and navigate programmatically between different states of a web application.
  • It provides methods to add, modify, or replace entries in the browser's history without causing a full page refresh.
  • With the History API, developers can create seamless user experiences by implementing features such as client-side routing, dynamic content loading, and browser navigation controls.
  • It consists of methods like pushState(), replaceState(), and events like popstate, which enable developers to manage browser history in response to user actions or application events.
  • To manipulate browser history, use methods like pushState(), replaceState(), and listen for the popstate event.
  • Use history.pushState(state, title, url) to add a new entry to the history stack.
  • Use history.replaceState(state, title, url) to modify the current entry in the history stack.
  • Listen for the popstate event to handle browser navigation changes.

Example:

history.pushState({ page: 1 }, 'Title', '/page1')
window.onpopstate = function (event) {
  console.log('Location: ' + document.location + ', State: ' + JSON.stringify(event.state))
}

Geolocation API

  • The Geolocation API allows web applications to retrieve the user's geographical location information, such as latitude and longitude coordinates, using the device's built-in location capabilities (like GPS).
  • It provides a simple interface for obtaining location data asynchronously, enabling developers to create location-aware web applications.
  • Geolocation API respects user privacy and requires explicit user consent before accessing location information.
  • Developers can use location data to customize content based on the user's location, provide location-based services, or display maps and directions within the application.
  • To get the user's location, use the navigator.geolocation object.
  • Call navigator.geolocation.getCurrentPosition() to retrieve the user's current position.
  • Handle the position data returned asynchronously in a callback function.

Example:

if (navigator.geolocation) {
  navigator.geolocation.getCurrentPosition(
    function (position) {
      console.log(
        'Latitude: ' + position.coords.latitude + ', Longitude: ' + position.coords.longitude
      )
    },
    function (error) {
      console.error('Error getting location:', error)
    }
  )
} else {
  console.error('Geolocation is not supported.')
}