What are the functional examples implemented by javascript?
JavaScript is a commonly used scripting language that is widely used in web page interactivity design and development. Today, we will introduce some practical functional examples implemented in JavaScript.
- Simple Calculator
JavaScript can be used to create simple calculators. This code snippet uses buttons and input boxes in HTML, and JavaScript to handle the calculator logic. The user enters numbers, operators, and operands, then clicks the equals sign to run the calculation and display the result.
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Simple Calculator</title> </head> <body> <form name="calculator"> <input type="text" name="answer" id="answer"> <br> <input type="button" value=" 1 " onclick="calculator.answer.value += '1'"> <input type="button" value=" 2 " onclick="calculator.answer.value += '2'"> <input type="button" value=" 3 " onclick="calculator.answer.value += '3'"> <input type="button" value=" + " onclick="calculator.answer.value += '+'"> <br> <input type="button" value=" 4 " onclick="calculator.answer.value += '4'"> <input type="button" value=" 5 " onclick="calculator.answer.value += '5'"> <input type="button" value=" 6 " onclick="calculator.answer.value += '6'"> <input type="button" value=" - " onclick="calculator.answer.value += '-'"> <br> <input type="button" value=" 7 " onclick="calculator.answer.value += '7'"> <input type="button" value=" 8 " onclick="calculator.answer.value += '8'"> <input type="button" value=" 9 " onclick="calculator.answer.value += '9'"> <input type="button" value=" * " onclick="calculator.answer.value += '*'"> <br> <input type="button" value=" c " onclick="calculator.answer.value = ''"> <input type="button" value=" 0 " onclick="calculator.answer.value += '0'"> <input type="button" value=" = " onclick="calculator.answer.value = eval(calculator.answer.value)"> <input type="button" value=" / " onclick="calculator.answer.value += '/'"> <br> </form> </body> </html>
- Countdown Timer
JavaScript can be used to create a countdown timer that counts down from a specified date and time until a specific target time. This code snippet uses a Date object to get the current time and target time, calculate the difference, and display it on the HTML page.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>CountDown Timer</title>
</head>
<body>
<div id="countdown"></div>
<script>
// Set the date we're counting down to
var countDownDate = new Date("Jan 1, 2022 00:00:00").getTime();
// Update the count down every 1 second
var x = setInterval(function() {
// Get today's date and time
var now = new Date().getTime();
// Find the distance between now and the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Output the result in an element with id="countdown"
document.getElementById("countdown").innerHTML = days + "d " + hours + "h "
+ minutes + "m " + seconds + "s ";
// If the count down is over, write some text
if (distance < 0) {
clearInterval(x);
document.getElementById("countdown").innerHTML = "EXPIRED";
}
}, 1000);
</script>
</body>
</html>- Image Carousel
JavaScript can be used to create an image carousel, where a group of images appear in rotation on a web page. This code snippet uses the image element in HTML and JavaScript logic to store a list of images in an array and update the current image at a specified interval.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Image Slider</title>
</head>
<body>
<div id="slider">
<img id="sliderImg" src="">
</div>
<script>
var images = [
"img1.jpg", "img2.jpg", "img3.jpg", "img4.jpg"
];
var current = 0;
function changeImage(){
current++;
if(current >= images.length){
current = 0;
}
document.getElementById("sliderImg").src = images[current];
}
setInterval(changeImage, 3000);
</script>
</body>
</html>- Form Validation
JavaScript can be used to validate user input to ensure that the format and content of the input data are correct. This code snippet uses HTML form elements and JavaScript logic to validate user input by checking each form element.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Form Validation</title>
<style>
.error{
color: red;
}
</style>
</head>
<body>
<form id="myForm">
<label for="name">Name:</label>
<input type="text" id="name" name="name"><br>
<label for="email">Email:</label>
<input type="email" id="email" name="email"><br>
<label for="phone">Phone:</label>
<input type="text" id="phone" name="phone"><br>
<input type="submit" value="Submit">
</form>
<script>
document.getElementById("myForm").addEventListener("submit", function(event){
var name = document.getElementById("name").value;
var email = document.getElementById("email").value;
var phone = document.getElementById("phone").value;
var nameError = document.getElementById("nameError");
var emailError = document.getElementById("emailError");
var phoneError = document.getElementById("phoneError");
if(!name){
nameError.innerHTML = "Please enter your name.";
event.preventDefault();
}
if(!email){
emailError.innerHTML = "Please enter your email.";
event.preventDefault();
}
if(!phone){
phoneError.innerHTML = "Please enter your phone number.";
event.preventDefault();
}
});
</script>
</body>
</html>Summary
These are functional examples implemented in JavaScript, covering practical functions such as calculators, countdown timers, image carousels, and form validation. Of course, this is just the tip of the iceberg of JavaScript application capabilities. JavaScript has many other uses and application scenarios in web design and development.
The above is the detailed content of What are the functional examples implemented by javascript?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1662
14
1418
52
1311
25
1261
29
1234
24
React's Role in HTML: Enhancing User Experience
Apr 09, 2025 am 12:11 AM
React combines JSX and HTML to improve user experience. 1) JSX embeds HTML to make development more intuitive. 2) The virtual DOM mechanism optimizes performance and reduces DOM operations. 3) Component-based management UI to improve maintainability. 4) State management and event processing enhance interactivity.
React and the Frontend: Building Interactive Experiences
Apr 11, 2025 am 12:02 AM
React is the preferred tool for building interactive front-end experiences. 1) React simplifies UI development through componentization and virtual DOM. 2) Components are divided into function components and class components. Function components are simpler and class components provide more life cycle methods. 3) The working principle of React relies on virtual DOM and reconciliation algorithm to improve performance. 4) State management uses useState or this.state, and life cycle methods such as componentDidMount are used for specific logic. 5) Basic usage includes creating components and managing state, and advanced usage involves custom hooks and performance optimization. 6) Common errors include improper status updates and performance issues, debugging skills include using ReactDevTools and Excellent
React's Ecosystem: Libraries, Tools, and Best Practices
Apr 18, 2025 am 12:23 AM
The React ecosystem includes state management libraries (such as Redux), routing libraries (such as ReactRouter), UI component libraries (such as Material-UI), testing tools (such as Jest), and building tools (such as Webpack). These tools work together to help developers develop and maintain applications efficiently, improve code quality and development efficiency.
React Components: Creating Reusable Elements in HTML
Apr 08, 2025 pm 05:53 PM
React components can be defined by functions or classes, encapsulating UI logic and accepting input data through props. 1) Define components: Use functions or classes to return React elements. 2) Rendering component: React calls render method or executes function component. 3) Multiplexing components: pass data through props to build a complex UI. The lifecycle approach of components allows logic to be executed at different stages, improving development efficiency and code maintainability.
Frontend Development with React: Advantages and Techniques
Apr 17, 2025 am 12:25 AM
The advantages of React are its flexibility and efficiency, which are reflected in: 1) Component-based design improves code reusability; 2) Virtual DOM technology optimizes performance, especially when handling large amounts of data updates; 3) The rich ecosystem provides a large number of third-party libraries and tools. By understanding how React works and uses examples, you can master its core concepts and best practices to build an efficient, maintainable user interface.
React: The Power of a JavaScript Library for Web Development
Apr 18, 2025 am 12:25 AM
React is a JavaScript library developed by Meta for building user interfaces, with its core being component development and virtual DOM technology. 1. Component and state management: React manages state through components (functions or classes) and Hooks (such as useState), improving code reusability and maintenance. 2. Virtual DOM and performance optimization: Through virtual DOM, React efficiently updates the real DOM to improve performance. 3. Life cycle and Hooks: Hooks (such as useEffect) allow function components to manage life cycles and perform side-effect operations. 4. Usage example: From basic HelloWorld components to advanced global state management (useContext and
React vs. Backend Frameworks: A Comparison
Apr 13, 2025 am 12:06 AM
React is a front-end framework for building user interfaces; a back-end framework is used to build server-side applications. React provides componentized and efficient UI updates, and the backend framework provides a complete backend service solution. When choosing a technology stack, project requirements, team skills, and scalability should be considered.
The Future of React: Trends and Innovations in Web Development
Apr 19, 2025 am 12:22 AM
React's future will focus on the ultimate in component development, performance optimization and deep integration with other technology stacks. 1) React will further simplify the creation and management of components and promote the ultimate in component development. 2) Performance optimization will become the focus, especially in large applications. 3) React will be deeply integrated with technologies such as GraphQL and TypeScript to improve the development experience.
