Database Interaction with Ajax in JavaScript

In modern web development, interacting with databases is essential for creating dynamic and data-driven applications. Ajax (Asynchronous JavaScript and XML) enables seamless communication between the client-side JavaScript code and the server, allowing for database interactions without page reloads.

Understanding Ajax Basics

Ajax facilitates asynchronous communication between the browser and the server, enabling the retrieval and manipulation of data without refreshing the entire web page. This is crucial for database interaction as it allows for real-time updates and dynamic content.

Setting Up a Database Environment

Before implementing database interaction with Ajax, it’s essential to have a database environment configured. This involves installing and configuring a database server such as MySQL, PostgreSQL, or MongoDB. Additionally, developers need to create a database and define tables to store the application’s data.

Creating a Database and Table

In this section, we focus on setting up a database and defining a table structure. Using SQL (Structured Query Language), developers create a database and specify tables with columns to organize and store data efficiently. The provided example demonstrates creating a database named mydatabase and a table named users with columns for id, name, and email.

				
					CREATE DATABASE mydatabase;
USE mydatabase;

CREATE TABLE users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(50),
  email VARCHAR(50)
);

Explanation:

  • CREATE DATABASE mydatabase;: This SQL statement creates a new database named mydatabase.
  • USE mydatabase;: This statement switches to the newly created database mydatabase, making it the active database for subsequent operations.
  • CREATE TABLE users (...);: This statement creates a table named users within the mydatabase database. The table has three columns: id, name, and email. The id column is an auto-incremented primary key, while name and email are varchar columns to store names and email addresses, respectively.

Establishing Server-Side Scripting

Server-side scripting is necessary to handle database operations requested by the client-side JavaScript code. In this example, we use Node.js with the Express framework to create an HTTP server. Additionally, a connection to the database is established using a database driver (such as mysql or pg for MySQL and PostgreSQL, respectively). This setup allows the server to execute queries and interact with the database.

				
					const express = require('express');
const bodyParser = require('body-parser');
const mysql = require('mysql');

const app = express();
const port = 3000;

app.use(bodyParser.json());

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: 'password',
  database: 'mydatabase'
});

connection.connect((err) => {
  if (err) throw err;
  console.log('Connected to the database.');
});

// Define API endpoints for CRUD operations

app.listen(port, () => {
  console.log(`Server running on port ${port}`);
});

This Node.js code sets up an Express server and establishes a connection to the MySQL database.

Explanation:

  • const express = require('express');: This line imports the Express.js framework, which simplifies the creation of web servers in Node.js.
  • const bodyParser = require('body-parser');: This line imports the body-parser middleware, which parses incoming request bodies in a middleware before handlers.
  • const mysql = require('mysql');: This line imports the MySQL module, which allows Node.js to interact with MySQL databases.
  • const app = express();: This creates an Express application instance.
  • const connection = mysql.createConnection({ ... });: This establishes a connection to the MySQL database named mydatabase using the provided credentials (host, user, password).
  • connection.connect((err) => { ... });: This connects to the MySQL database. If an error occurs, it throws an error; otherwise, it logs “Connected to the database.” to the console.
  • app.listen(port, () => { ... });: This starts the Express server listening on port 3000. When the server starts, it logs “Server running on port 3000” to the console.

Handling Ajax Requests

With the server-side environment set up, we focus on the client-side implementation. The provided HTML page contains JavaScript code responsible for sending Ajax requests to the server. The fetch API is used to perform HTTP requests asynchronously. When the server responds with data, JavaScript dynamically updates the web page content, providing real-time feedback to the user.

				
					<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Database Interaction</title>
</head>
<body>
  <h1>Database Interaction with Ajax</h1>
  <div id="users"></div> <script type="litespeed/javascript">function getUsers(){fetch('/users').then(response=>response.json()).then(data=>{const usersDiv=document.getElementById('users');usersDiv.innerHTML='';data.forEach(user=>{usersDiv.innerHTML+=`<p>${user.name} - ${user.email}</p>`})}).catch(error=>console.error('Error fetching users:',error))}
getUsers()</script> <script data-no-optimize="1">!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).LazyLoad=e()}(this,function(){"use strict";function e(){return(e=Object.assign||function(t){for(var e=1;e<arguments.length;e++){var n,a=arguments[e];for(n in a)Object.prototype.hasOwnProperty.call(a,n)&&(t[n]=a[n])}return t}).apply(this,arguments)}function i(t){return e({},it,t)}function o(t,e){var n,a="LazyLoad::Initialized",i=new t(e);try{n=new CustomEvent(a,{detail:{instance:i}})}catch(t){(n=document.createEvent("CustomEvent")).initCustomEvent(a,!1,!1,{instance:i})}window.dispatchEvent(n)}function l(t,e){return t.getAttribute(gt+e)}function c(t){return l(t,bt)}function s(t,e){return function(t,e,n){e=gt+e;null!==n?t.setAttribute(e,n):t.removeAttribute(e)}(t,bt,e)}function r(t){return s(t,null),0}function u(t){return null===c(t)}function d(t){return c(t)===vt}function f(t,e,n,a){t&&(void 0===a?void 0===n?t(e):t(e,n):t(e,n,a))}function _(t,e){nt?t.classList.add(e):t.className+=(t.className?" ":"")+e}function v(t,e){nt?t.classList.remove(e):t.className=t.className.replace(new RegExp("(^|\\s+)"+e+"(\\s+|$)")," ").replace(/^\s+/,"").replace(/\s+$/,"")}function g(t){return t.llTempImage}function b(t,e){!e||(e=e._observer)&&e.unobserve(t)}function p(t,e){t&&(t.loadingCount+=e)}function h(t,e){t&&(t.toLoadCount=e)}function n(t){for(var e,n=[],a=0;e=t.children[a];a+=1)"SOURCE"===e.tagName&&n.push(e);return n}function m(t,e){(t=t.parentNode)&&"PICTURE"===t.tagName&&n(t).forEach(e)}function a(t,e){n(t).forEach(e)}function E(t){return!!t[st]}function I(t){return t[st]}function y(t){return delete t[st]}function A(e,t){var n;E(e)||(n={},t.forEach(function(t){n[t]=e.getAttribute(t)}),e[st]=n)}function k(a,t){var i;E(a)&&(i=I(a),t.forEach(function(t){var e,n;e=a,(t=i[n=t])?e.setAttribute(n,t):e.removeAttribute(n)}))}function L(t,e,n){_(t,e.class_loading),s(t,ut),n&&(p(n,1),f(e.callback_loading,t,n))}function w(t,e,n){n&&t.setAttribute(e,n)}function x(t,e){w(t,ct,l(t,e.data_sizes)),w(t,rt,l(t,e.data_srcset)),w(t,ot,l(t,e.data_src))}function O(t,e,n){var a=l(t,e.data_bg_multi),i=l(t,e.data_bg_multi_hidpi);(a=at&&i?i:a)&&(t.style.backgroundImage=a,n=n,_(t=t,(e=e).class_applied),s(t,ft),n&&(e.unobserve_completed&&b(t,e),f(e.callback_applied,t,n)))}function N(t,e){!e||0<e.loadingCount||0<e.toLoadCount||f(t.callback_finish,e)}function C(t,e,n){t.addEventListener(e,n),t.llEvLisnrs[e]=n}function M(t){return!!t.llEvLisnrs}function z(t){if(M(t)){var e,n,a=t.llEvLisnrs;for(e in a){var i=a[e];n=e,i=i,t.removeEventListener(n,i)}delete t.llEvLisnrs}}function R(t,e,n){var a;delete t.llTempImage,p(n,-1),(a=n)&&--a.toLoadCount,v(t,e.class_loading),e.unobserve_completed&&b(t,n)}function T(o,r,c){var l=g(o)||o;M(l)||function(t,e,n){M(t)||(t.llEvLisnrs={});var a="VIDEO"===t.tagName?"loadeddata":"load";C(t,a,e),C(t,"error",n)}(l,function(t){var e,n,a,i;n=r,a=c,i=d(e=o),R(e,n,a),_(e,n.class_loaded),s(e,dt),f(n.callback_loaded,e,a),i||N(n,a),z(l)},function(t){var e,n,a,i;n=r,a=c,i=d(e=o),R(e,n,a),_(e,n.class_error),s(e,_t),f(n.callback_error,e,a),i||N(n,a),z(l)})}function G(t,e,n){var a,i,o,r,c;t.llTempImage=document.createElement("IMG"),T(t,e,n),E(c=t)||(c[st]={backgroundImage:c.style.backgroundImage}),o=n,r=l(a=t,(i=e).data_bg),c=l(a,i.data_bg_hidpi),(r=at&&c?c:r)&&(a.style.backgroundImage='url("'.concat(r,'")'),g(a).setAttribute(ot,r),L(a,i,o)),O(t,e,n)}function D(t,e,n){var a;T(t,e,n),a=e,e=n,(t=It[(n=t).tagName])&&(t(n,a),L(n,a,e))}function V(t,e,n){var a;a=t,(-1<yt.indexOf(a.tagName)?D:G)(t,e,n)}function F(t,e,n){var a;t.setAttribute("loading","lazy"),T(t,e,n),a=e,(e=It[(n=t).tagName])&&e(n,a),s(t,vt)}function j(t){t.removeAttribute(ot),t.removeAttribute(rt),t.removeAttribute(ct)}function P(t){m(t,function(t){k(t,Et)}),k(t,Et)}function S(t){var e;(e=At[t.tagName])?e(t):E(e=t)&&(t=I(e),e.style.backgroundImage=t.backgroundImage)}function U(t,e){var n;S(t),n=e,u(e=t)||d(e)||(v(e,n.class_entered),v(e,n.class_exited),v(e,n.class_applied),v(e,n.class_loading),v(e,n.class_loaded),v(e,n.class_error)),r(t),y(t)}function $(t,e,n,a){var i;n.cancel_on_exit&&(c(t)!==ut||"IMG"===t.tagName&&(z(t),m(i=t,function(t){j(t)}),j(i),P(t),v(t,n.class_loading),p(a,-1),r(t),f(n.callback_cancel,t,e,a)))}function q(t,e,n,a){var i,o,r=(o=t,0<=pt.indexOf(c(o)));s(t,"entered"),_(t,n.class_entered),v(t,n.class_exited),i=t,o=a,n.unobserve_entered&&b(i,o),f(n.callback_enter,t,e,a),r||V(t,n,a)}function H(t){return t.use_native&&"loading"in HTMLImageElement.prototype}function B(t,i,o){t.forEach(function(t){return(a=t).isIntersecting||0<a.intersectionRatio?q(t.target,t,i,o):(e=t.target,n=t,a=i,t=o,void(u(e)||(_(e,a.class_exited),$(e,n,a,t),f(a.callback_exit,e,n,t))));var e,n,a})}function J(e,n){var t;et&&!H(e)&&(n._observer=new IntersectionObserver(function(t){B(t,e,n)},{root:(t=e).container===document?null:t.container,rootMargin:t.thresholds||t.threshold+"px"}))}function K(t){return Array.prototype.slice.call(t)}function Q(t){return t.container.querySelectorAll(t.elements_selector)}function W(t){return c(t)===_t}function X(t,e){return e=t||Q(e),K(e).filter(u)}function Y(e,t){var n;(n=Q(e),K(n).filter(W)).forEach(function(t){v(t,e.class_error),r(t)}),t.update()}function t(t,e){var n,a,t=i(t);this._settings=t,this.loadingCount=0,J(t,this),n=t,a=this,Z&&window.addEventListener("online",function(){Y(n,a)}),this.update(e)}var Z="undefined"!=typeof window,tt=Z&&!("onscroll"in window)||"undefined"!=typeof navigator&&/(gle|ing|ro)bot|crawl|spider/i.test(navigator.userAgent),et=Z&&"IntersectionObserver"in window,nt=Z&&"classList"in document.createElement("p"),at=Z&&1<window.devicePixelRatio,it={elements_selector:".lazy",container:tt||Z?document:null,threshold:300,thresholds:null,data_src:"src",data_srcset:"srcset",data_sizes:"sizes",data_bg:"bg",data_bg_hidpi:"bg-hidpi",data_bg_multi:"bg-multi",data_bg_multi_hidpi:"bg-multi-hidpi",data_poster:"poster",class_applied:"applied",class_loading:"litespeed-loading",class_loaded:"litespeed-loaded",class_error:"error",class_entered:"entered",class_exited:"exited",unobserve_completed:!0,unobserve_entered:!1,cancel_on_exit:!0,callback_enter:null,callback_exit:null,callback_applied:null,callback_loading:null,callback_loaded:null,callback_error:null,callback_finish:null,callback_cancel:null,use_native:!1},ot="src",rt="srcset",ct="sizes",lt="poster",st="llOriginalAttrs",ut="loading",dt="loaded",ft="applied",_t="error",vt="native",gt="data-",bt="ll-status",pt=[ut,dt,ft,_t],ht=[ot],mt=[ot,lt],Et=[ot,rt,ct],It={IMG:function(t,e){m(t,function(t){A(t,Et),x(t,e)}),A(t,Et),x(t,e)},IFRAME:function(t,e){A(t,ht),w(t,ot,l(t,e.data_src))},VIDEO:function(t,e){a(t,function(t){A(t,ht),w(t,ot,l(t,e.data_src))}),A(t,mt),w(t,lt,l(t,e.data_poster)),w(t,ot,l(t,e.data_src)),t.load()}},yt=["IMG","IFRAME","VIDEO"],At={IMG:P,IFRAME:function(t){k(t,ht)},VIDEO:function(t){a(t,function(t){k(t,ht)}),k(t,mt),t.load()}},kt=["IMG","IFRAME","VIDEO"];return t.prototype={update:function(t){var e,n,a,i=this._settings,o=X(t,i);{if(h(this,o.length),!tt&&et)return H(i)?(e=i,n=this,o.forEach(function(t){-1!==kt.indexOf(t.tagName)&&F(t,e,n)}),void h(n,0)):(t=this._observer,i=o,t.disconnect(),a=t,void i.forEach(function(t){a.observe(t)}));this.loadAll(o)}},destroy:function(){this._observer&&this._observer.disconnect(),Q(this._settings).forEach(function(t){y(t)}),delete this._observer,delete this._settings,delete this.loadingCount,delete this.toLoadCount},loadAll:function(t){var e=this,n=this._settings;X(t,n).forEach(function(t){b(t,e),V(t,n,e)})},restoreAll:function(){var e=this._settings;Q(e).forEach(function(t){U(t,e)})}},t.load=function(t,e){e=i(e);V(t,e)},t.resetStatus=function(t){r(t)},Z&&function(t,e){if(e)if(e.length)for(var n,a=0;n=e[a];a+=1)o(t,n);else o(t,e)}(t,window.lazyLoadOptions),t});!function(e,t){"use strict";function a(){t.body.classList.add("litespeed_lazyloaded")}function n(){console.log("[LiteSpeed] Start Lazy Load Images"),d=new LazyLoad({elements_selector:"[data-lazyloaded]",callback_finish:a}),o=function(){d.update()},e.MutationObserver&&new MutationObserver(o).observe(t.documentElement,{childList:!0,subtree:!0,attributes:!0})}var d,o;e.addEventListener?e.addEventListener("load",n,!1):e.attachEvent("onload",n)}(window,document);</script><script data-no-optimize="1">var litespeed_vary=document.cookie.replace(/(?:(?:^|.*;\s*)_lscache_vary\s*\=\s*([^;]*).*$)|^.*$/,"");litespeed_vary||fetch("/wp-content/plugins/litespeed-cache/guest.vary.php",{method:"POST",cache:"no-cache",redirect:"follow"}).then(e=>e.json()).then(e=>{console.log(e),e.hasOwnProperty("reload")&&"yes"==e.reload&&(sessionStorage.setItem("litespeed_docref",document.referrer),window.location.reload(!0))});</script><script data-optimized="1" type="litespeed/javascript" data-src="https://diginode.in/wp-content/litespeed/js/96d0e6d4ba93134cbdab615e06eb2824.js?ver=a1a89"></script><script>const litespeed_ui_events=["mouseover","click","keydown","wheel","touchmove","touchstart"];var urlCreator=window.URL||window.webkitURL;function litespeed_load_delayed_js_force(){console.log("[LiteSpeed] Start Load JS Delayed"),litespeed_ui_events.forEach(e=>{window.removeEventListener(e,litespeed_load_delayed_js_force,{passive:!0})}),document.querySelectorAll("iframe[data-litespeed-src]").forEach(e=>{e.setAttribute("src",e.getAttribute("data-litespeed-src"))}),"loading"==document.readyState?window.addEventListener("DOMContentLoaded",litespeed_load_delayed_js):litespeed_load_delayed_js()}litespeed_ui_events.forEach(e=>{window.addEventListener(e,litespeed_load_delayed_js_force,{passive:!0})});async function litespeed_load_delayed_js(){let t=[];for(var d in document.querySelectorAll('script[type="litespeed/javascript"]').forEach(e=>{t.push(e)}),t)await new Promise(e=>litespeed_load_one(t[d],e));document.dispatchEvent(new Event("DOMContentLiteSpeedLoaded")),window.dispatchEvent(new Event("DOMContentLiteSpeedLoaded"))}function litespeed_load_one(t,e){console.log("[LiteSpeed] Load ",t);var d=document.createElement("script");d.addEventListener("load",e),d.addEventListener("error",e),t.getAttributeNames().forEach(e=>{"type"!=e&&d.setAttribute("data-src"==e?"src":e,t.getAttribute(e))});let a=!(d.type="text/javascript");!d.src&&t.textContent&&(d.src=litespeed_inline2src(t.textContent),a=!0),t.after(d),t.remove(),a&&e()}function litespeed_inline2src(t){try{var d=urlCreator.createObjectURL(new Blob([t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1")],{type:"text/javascript"}))}catch(e){d="data:text/javascript;base64,"+btoa(t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1"))}return d}</script></body>
</html>

This HTML page contains JavaScript code to fetch users from the server using Ajax and display them on the web page.

Explanation:

  • This HTML page contains JavaScript code for fetching users from the server using Ajax.
  • fetch('/users'): This initiates a GET request to the /users endpoint on the server.
  • .then(response => response.json()): This converts the response from the server to JSON format.
  • .then(data => { ... }): This processes the JSON data received from the server.
  • const usersDiv = document.getElementById('users');: This retrieves the HTML element with the id ‘users’.
  • data.forEach(user => { ... }): This iterates over each user object in the data array received from the server.
  • usersDiv.innerHTML += <p>${user.name} – ${user.email}</p>;: This dynamically adds HTML content to the ‘users’ div, displaying each user’s name and email as paragraphs.

Performing CRUD Operations

CRUD operations (Create, Read, Update, Delete) are fundamental database operations necessary for interacting with data. In this section, we define API endpoints on the server to handle these operations. For example, a GET request to /users retrieves all users from the database table users. The server executes SQL queries accordingly and sends the results back to the client as JSON data.

				
					// GET all users
app.get('/users', (req, res) => {
  connection.query('SELECT * FROM users', (err, results) => {
    if (err) throw err;
    res.json(results);
  });
});

This code defines an API endpoint to retrieve all users from the users table and sends the results as JSON.

Explanation:

  • This code defines an API endpoint for handling GET requests to the /users route.
  • When a GET request is made to /users, the function specified as the second argument is executed.
  • connection.query('SELECT * FROM users', (err, results) => { ... }): This executes a SQL query to select all records from the users table in the database.
  • If an error occurs during the query execution, it is thrown.
  • If the query is successful, the results are sent back to the client as JSON using res.json(results).

Database interaction with Ajax in JavaScript empowers developers to build dynamic and responsive web applications. By combining the asynchronous nature of Ajax requests with server-side scripting and database operations, developers can create applications that provide seamless user experiences. This chapter covered the foundational concepts and practical implementation of database interaction with Ajax, paving the way for further exploration and development in web development projects. Happy coding !❤️

Table of Contents

Popular Tutorials

Contact here

Copyright © 2025 Diginode

Made with ❤️ in India

Home
Roadmap
ATS Resume
Playground
Resources