Discount calculator built with HTML, CSS and JavaScript
This article will walk through a discount calculator built using HTML, CSS and JavaScript. We'll break down the code piece by piece, explaining how each part works. In addition, instructions will be provided on how to test the calculator yourself, and some suggestions for code improvements will be provided.
[Test the Code here](Test the Code)
Calculator function
This calculator is designed to help users calculate the final price of an item after applying discounts, taxes, and any additional fees. It accepts inputs of original price, quantity, discount percentage, tax percentage and additional charges. It then calculates the total cost based on these inputs.
HTML structure
The following is the basic structure of the HTML code:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>高级折扣计算器</title>
<link rel="stylesheet" href="style.css"> </head>
<body class="discount-body">
<h1 id="高级折扣计算器">高级折扣计算器</h1>
<div class="container discount-container">
</div>
<div id="discount-result"></div>
<script src="script.js"></script>
</body>
</html>
Instructions:
-
DOCTYPE and HTML tags : The
declaration defines the document type, in this case HTML5. The <code>tag contains all HTML content. -
Head Section: Inside the
tag, we have meta tags to set the charset and viewport for responsive design. The<title></title>tag defines the page title displayed in the browser tab. -
Body Section: The body of the page contains the actual content that the user will interact with. Here, we use the
<h1></h1>tag as the main title and<div> as the container containing the form elements. <hr> <p><strong>CSS style</strong></p> <p>Now, let’s discuss the CSS for styling the calculator: </p> <pre class='brush:php;toolbar:false;'>body.discount-body { font-family: 'Arial', sans-serif; margin: 0; padding: 20px; background-color: #f3f4f6; color: #333; box-sizing: border-box; }</pre> <p><strong>Segmentation: </strong></p> <ul> <li> <code>body.discount-body: We apply common styles to the body, such as setting the font family to Arial, adding padding around the content, and setting a light background color.box-sizing: border-box;Make sure padding and borders are included in the overall width and height of the element. -
h1.discount-heading: The title is centered, the color is green (#28a745), there is a margin at the bottom, and the font size is 24px. -
.container.discount-container: This section styles the container in which all form inputs and buttons are located. It has a maximum width of 500px, is centered horizontally usingmargin: 0 auto;, and has a green border.box-shadowCreate a subtle shadow around the container to give it depth. -
Element Selection: We use
document.getElementById()to retrieve the value from the form input. - Validation: We check if the input value is a valid number. If any value is invalid, we display an alert to the user.
- Calculation: The total price is calculated by multiplying the original price by the quantity. We then apply the discount, calculate taxes, and add any additional fees.
-
Display results: The results are displayed in the div with id
discount-result. We use.innerHTMLto dynamically update content and.style.display = 'block'to display results. - Non-negative number validation: Ensures that users cannot enter negative numbers for price, quantity or fee.
- Optional Taxes: Tax and surcharge fields can be made optional by setting default values or adding more complex input handling.
- User Feedback: For invalid input, consider displaying the message on the page itself, which will be less intrusive.
h1.discount-heading {
text-align: center;
color: #28a745;
margin-bottom: 15px;
font-size: 24px;
}
.container.discount-container {
max-width: 500px;
margin: 0 auto;
background-color: #ffffff;
padding: 20px;
border-radius: 10px;
box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
border: 2px solid #28a745;
}
JavaScript function
The main functionality of the calculator is handled by JavaScript. The following is the calculateDiscount function:
function calculateDiscount() {
// ... (代码与原文相同) ...
}
Segmentation:
Suggestions for improvement
The code works well, but there is always room for improvement. Here are some suggestions:
Share your thoughts
What other improvements do you think could be made to this code? Please leave your suggestions in the comments below and let's improve this calculator together!
[Test the Code here](Test the Code)
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