This calculator is a compact, responsive, blue-themed web calculator with basic arithmetic, expression evaluation, and an optional Plotly.js graphing panel for visualizing functions; it’s built to fit between two WordPress sidebars.
How to use the Blue Calculator: A Complete Guide
Introduction
The Blue Calculator is a compact, easy-to-use web calculator designed for embedding into a WordPress site’s content area (between sidebars). It combines a traditional on-screen keypad with free-text expression input and a Plotly.js panel to visualize functions. This guide explains what the calculator does, how to embed and use it, and practical tips to get the most from its features.
Who this is for
If you run a WordPress blog, educational site, or documentation page and want an attractive interactive calculator that fits in the content column, this tool is for you. It’s ideal for teaching arithmetic, checking quick calculations, and plotting simple mathematical functions for demonstration.
Layout and sizing — built for WordPress
The calculator is sized to match standard WordPress content areas. Its wrapper uses max-width: 720px and width: 100%so it will sit comfortably between common sidebars without overlapping. The height is responsive, and the Plotly chart area adapts to the container’s width. The background is white, ensuring good contrast with most themes.
Core features
- Standard functions — addition, subtraction, multiplication, division, parentheses, decimal numbers, clear, and backspace.
- Expression input — type complex expressions like
3*(2+4)/5 - 0.75. - Evaluate — compute the expression and show the result instantly.
- Plot toggle — graph expressions treated as
y = f(x)using Plotly.js. - History — clickable recent calculations to reuse past expressions.
- Responsive blue UI — blue buttons on a white background.
Using the calculator
Basic calculations
Type your expression in the input using the keypad or keyboard. Press = or “Evaluate.” The result appears below the input. Use C to clear or backspace to remove the last character.
Parentheses and decimals
The calculator evaluates with JavaScript precedence; use parentheses to group and decimals such as 2.5 * (4 - 1).
Plotting with Plotly.js
Enter an expression in terms of x, for example sin(x) or x^2, then click the Plot toggle. The calculator samples the function over a default x-range (−10 to 10) and draws an interactive Plotly chart below the keypad. You can pan, zoom, and hover to inspect values.
Supported functions match JavaScript’s Math names: sin, cos, tan, exp, log, sqrt. The code converts caret ^ to exponent ** for evaluation. Avoid inputs that are arbitrary JavaScript.
History and reuse
Each evaluation is recorded in the history area. Click an item to load it back into the input for editing or re-evaluation.
Practical examples
- Quick arithmetic:
45.3 * 1.2 - Parentheses:
(12+8)/(3-1) - Compound:
3*(2+4) - 5^2 - Plot:
sin(x)orx^3 - 6*x
Accessibility and UX
Buttons are large and readable; keyboard input is supported. Colors provide sufficient contrast on a white background. The layout uses clear typography to keep the interface friendly.
Implementation notes
The calculator uses a small JavaScript evaluator and the Plotly.js CDN for graphs. It sanitizes input by allowing only numbers, operators, parentheses, and explicit function names to reduce injection risk. Still, embed in a trusted environment and use Content Security Policy (CSP) if possible.
Embedding into WordPress
Paste the provided HTML/JS into a Custom HTML block or a theme’s custom code area. The inline styles and Plotly CDN mean it renders without extra dependencies. If you use cache or optimization plugins, clear caches after adding the code.
Troubleshooting
- If a plot fails, confirm Plotly is loaded.
- In very narrow content columns, reduce
max-width. NaNorInfinitysignals invalid operations (division by zero or domain errors).
Security and limitations
This tool evaluates expressions in the browser using JavaScript. Although it filters input, avoid evaluating untrusted code. For stricter math parsing, integrate a vetted parsing library.
Advanced tips and customization
For site owners who want to customize behavior, the code exposes a few knobs: change max-width to match your theme, update xRange for plotting, or increase sample density for smoother curves. The calculator has a short history buffer; developers can increase stored items or persist history to localStorage to keep history across sessions.
To improve accessibility, add aria-label attributes to buttons and ensure keyboard focus styles are visible. For multilingual sites, localize labels and replace decimal separators if your locale uses commas. If you need scientific notation output, format the result with toExponential().
Performance notes: Plotly renders efficiently for moderate sample sizes (200–1000 points). For heavy workloads, consider delegating to a backend API and sending only the reduced dataset to the browser.
SEO and engagement: place the calculator near explanatory text or examples to keep visitors interacting longer. Use descriptive headings and caption the plot area so screen readers and search engines better understand the content. A short example list near the calculator increases dwell time and usefulness.
Maintenance
Keep the Plotly CDN link up to date; clear caches after WordPress or plugin updates and when you change the code.
Disclaimer
The Blue Calculator is provided for convenience and educational purposes only. Results may be subject to floating-point rounding and are not guaranteed for financial, medical, legal, or other critical decisions. Use professional tools for high-stakes calculations.
FAQ
Q: Can it handle complex numbers?
A: No — it evaluates real-valued expressions only.
Q: Which functions work in plots?
A: Common Math functions such as sin, cos, tan, exp, log, and sqrt are supported.
Q: Is it mobile-friendly?
A: Yes — it’s responsive, but extreme narrowness can reduce usability.
Q: Can I change the color theme?
A: Yes — edit CSS variables near the top of the code to change the primary blue.
Q: Where do I paste the code in WordPress?
A: Use a Custom HTML block inside the block editor or a child theme file that renders within the content area.