Building a powerful calculator chrome extension

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calculator chrome extension
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A calculator Chrome extension transforms productivity by embedding essential computational tools directly into browsing workflows. Beyond basic arithmetic, these extensions integrate scientific functions, unit conversions, and real-time financial calculations, catering to professionals, students, and developers alike. This guide explores their core functionalities, technical implementation, and design principles to create seamless, high-performance tools that enhance user efficiency without disrupting workflows.

The modern calculator extension extends far beyond traditional desktop calculators, incorporating dynamic features like API-driven currency exchange, customizable unit systems, and accessibility-focused interfaces. Whether optimizing for performance, security, or monetization, developers must balance technical precision with intuitive user experience. From manifest configurations to monetization strategies, this discussion provides a structured roadmap for crafting extensions that stand out in Chrome’s competitive ecosystem.

calculator chrome extension

Overview of Calculator Chrome Extensions

Calculator Chrome extensions enhance productivity by providing quick, accessible computational tools directly within the browser. These extensions eliminate the need for external applications or manual calculations, offering a seamless experience for users across various domains—from basic arithmetic to complex scientific and financial operations. Their integration with Chrome’s ecosystem ensures compatibility with web-based workflows, making them indispensable for professionals, students, and casual users alike.

The core functionalities of a calculator Chrome extension typically include:

  • Basic arithmetic operations (addition, subtraction, multiplication, division) with support for decimals, fractions, and percentages.
  • Advanced mathematical functions such as exponents, roots, logarithms, and trigonometric operations (sine, cosine, tangent).
  • Scientific and engineering calculations, including constants (π, e), statistical functions (mean, standard deviation), and matrix operations.
  • Unit conversions for length, weight, temperature, volume, and time, often with real-time currency exchange rates.
  • Memory and history features to store intermediate results, recall previous calculations, or export data.
  • Customizable themes and layouts to adapt to user preferences, including dark mode and keyboard shortcuts.
  • Integration with other tools such as clipboard functionality, unit synchronization, or compatibility with cloud services for saving calculations.

    • Core Functionalities of Calculator Chrome Extensions

    Calculator extensions are designed to cater to diverse user needs, ranging from simplicity to specialized computations. Below is a breakdown of their primary features:

    Basic Arithmetic Operations
    Standard calculator functions form the foundation of any Chrome extension. These include:

  • Four fundamental operations: Addition (+), subtraction (−), multiplication (×), and division (÷).
  • Decimal and fractional support: Handling precise values (e.g., 3.14159 or ½).
  • Percentage calculations: Essential for financial and statistical analyses (e.g., discounts, interest rates).
  • Memory functions: Store, recall, and clear values (e.g., M+, M−, MR, MC).

    • Scientific and Engineering Tools
    Extensions targeting advanced users incorporate specialized functions:

  • Exponential and logarithmic operations: Calculating xy, natural logarithms (ln), and base-10 logarithms (log).
  • Trigonometric functions: Sine (sin), cosine (cos), tangent (tan), and their inverses, with support for degrees and radians.
  • Statistical computations: Mean, median, mode, standard deviation, and variance.
  • Matrix operations: Addition, multiplication, determinants, and inverses for linear algebra applications.

    • Unit Conversions and Currency Exchange
    These features address real-world practicality by converting between:

  • Physical units: Metric to imperial (e.g., kilometers to miles, Celsius to Fahrenheit) and vice versa.
  • Volume and weight: Liters to gallons, grams to ounces.
  • Currency exchange: Real-time or predefined rates for major and minor currencies (e.g., USD to EUR, JPY to GBP).
  • Time and date: Seconds to hours, UTC offsets, or calendar conversions.

    • Additional Productivity Features
    To enhance usability, extensions often include:

  • Keyboard shortcuts: Quick access to functions (e.g., Ctrl+Enter to compute).
  • History and export: Save calculation logs as CSV, JSON, or text files.
  • Custom themes: Light/dark mode, font size adjustments, or color schemes.
  • Accessibility options: Screen reader support, high-contrast modes, or touch-friendly interfaces.
    • Below is a structured comparison of three widely used calculator extensions, evaluated based on features, user feedback, and technical specifications. Data is sourced from the Chrome Web Store (as of latest verified updates) and aggregated user reviews.
    Feature Calculator by Everyday Math Advanced Calculator Scientific Calculator
    Basic Arithmetic ✓ Addition, subtraction, multiplication, division
    ✓ Decimal/fraction support
    ✓ Percentage calculations    		 ✓ All basic operations
    ✓ Memory functions (M+, M−, MR, MC)
    ✓ Keyboard input support    		 ✓ Full basic operations
    ✓ Scientific notation (e.g., 1.23e4)
    Scientific Functions ✗ Limited to basic operations ✓ Trigonometric (sin, cos, tan)
    ✓ Logarithms (ln, log)
    ✓ Exponents and roots    		 ✓ Full scientific suite
    ✓ Statistical functions (mean, std dev)
    ✓ Matrix operations
    Unit Conversions ✓ Length, weight, temperature
    ✓ Currency exchange (static rates)    		 ✓ Comprehensive unit library
    ✓ Real-time currency API (optional)    		 ✓ Basic conversions
    ✗ No currency exchange
    User Ratings (Chrome Web Store) 4.5/5 (12,000+ reviews) 4.7/5 (8,500+ reviews) 4.3/5 (5,200+ reviews)
    Installation Size 1.2 MB 2.8 MB 3.5 MB
    Last Update Date June 2023 March 2024 October 2023
    Unique Features ✓ Dark mode toggle
    ✓ Clipboard history    		 ✓ Customizable themes
    ✓ Cloud sync (premium)    		 ✓ Offline functionality
    ✓ Programmer mode (hex, binary)
    Key Observations from the Comparison
  • "Advanced Calculator" stands out for its balance of scientific features and user ratings, making it ideal for professionals requiring both precision and ease of use.
  • "Scientific Calculator" is the most feature-rich but lacks real-time currency updates, targeting users who prioritize engineering or mathematical computations.
  • "Calculator by Everyday Math" is lightweight and suitable for basic tasks, with a focus on accessibility and minimalism.
  • Currency exchange is a differentiating factor; extensions like Advanced Calculator offer optional real-time updates via APIs, while others rely on static databases.
    • Note: User ratings reflect overall satisfaction, but feature parity should align with specific use cases. For example, a developer may prioritize matrix operations over currency conversion, whereas a traveler would value real-time exchange rates.

    Technical Implementation and Development of a Calculator Chrome Extension

    The development of a Calculator Chrome Extension relies on a structured technical stack that integrates Chrome’s extension APIs, modern JavaScript, and declarative configurations. This section outlines the essential components—including the manifest file, core APIs (`chrome.storage`, `chrome.runtime`), and event-driven interactions—required to build a functional, user-preference-aware calculator. The implementation leverages plain JavaScript for logic, HTML/CSS for the UI, and Chrome’s storage mechanisms for persistence, ensuring compatibility with the extension ecosystem.

    The technical foundation of a Chrome extension calculator involves three primary layers:
    1. Manifest Configuration: Defines permissions, APIs, and resource declarations.
    2. Core Functionality: Implements arithmetic operations via JavaScript and handles user input through event listeners.
    3. Data Persistence: Uses `chrome.storage.local` to save preferences (e.g., theme, history) across sessions.

    Manifest File Configuration

    The manifest file (`manifest.json`) serves as the extension’s configuration blueprint, specifying metadata, permissions, and API access. For a calculator extension, critical fields include:
  • `manifest_version`: Declares compatibility with Chrome’s manifest schema (v3 for latest features).
  • `name`/`version`: Identifies the extension and its version.
  • `permissions`: Grants access to necessary APIs (e.g., `storage` for local persistence).
  • `background`: Defines the service worker script handling background tasks.
  • `action`: Configures the extension’s browser action (e.g., popup UI).

    • Example Manifest Structure:
    ```json
    {
    "manifest_version": 3,
    "name": "Chrome Calculator",
    "version": "1.0",
    "description": "A lightweight calculator extension with preference storage.",
    "permissions": ["storage"],
    "background": {
    "service_worker": "background.js"
    },
    "action": {
    "default_popup": "popup.html",
    "default_icon": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
    }
    },
    "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
    }
    }
    ```
    Key Considerations:

  • Manifest V3: Enforces service workers for background scripts, improving performance and security.
  • Storage Permission: Required for `chrome.storage.local` to save user preferences.
  • Popup UI: Defined via `popup.html`, which hosts the calculator interface.

    • Core APIs and Event-Driven Interactions

    Chrome extensions utilize asynchronous APIs to interact with the browser and user data. For a calculator, the following APIs are pivotal:

    1. `chrome.runtime`

  • Manages extension lifecycle events (e.g., `onInstalled`, `onMessage`).
  • Example: Listening for button clicks in the popup:
    • ```javascript
    document.addEventListener('DOMContentLoaded', () => {
    const buttons = document.querySelectorAll('button');
    buttons.forEach(button => {
    button.addEventListener('click', (e) => {
    const value = e.target.textContent;
    updateDisplay(value); // Custom function to handle input
    });
    });
    });
    ```

    2. `chrome.storage.local`

  • Stores user preferences (e.g., dark mode, history) persistently.
  • CRUD Operations:
    • ```javascript
    // Save preference
    chrome.storage.local.set({ theme: 'dark' }, () => {
    console.log('Theme saved');
    });

    // Retrieve preference
    chrome.storage.local.get(['theme'], (result) => {
    applyTheme(result.theme); // Apply saved theme
    });
    ```

    3. Message Passing (`chrome.runtime.sendMessage`)

  • Enables communication between the popup and background script (e.g., for complex calculations).
  • Example: Sending a calculation request:
    • ```javascript
    chrome.runtime.sendMessage({ action: 'calculate', expr: '2+3' }, (response) => {
    displayResult(response.result);
    });
    ```

    Event Listeners for Calculator Buttons
    The calculator’s UI responds to user interactions via event listeners attached to buttons (e.g., digits, operators). A typical implementation:

  • Input Handling: Captures clicks on number/operator buttons and updates the display.
  • Operation Execution: Triggers calculations when the "=" button is pressed.
  • Clear/Backspace: Resets or modifies the current input.

    • Example HTML/CSS Structure:
    ```html

    ```
    ```css
    .calculator {
    font-family: Arial, sans-serif;
    max-width: 300px;
    padding: 10px;
    }
    #display {
    width: 100%;
    height: 40px;
    text-align: right;
    font-size: 24px;
    }
    .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 5px;
    }
    button {
    padding: 15px;
    font-size: 18px;
    cursor: pointer;
    }
    ```

    Arithmetic Logic and Storage Integration

    The calculator’s core logic processes user input and performs computations using JavaScript’s `eval()` (with caution) or a custom parser for security. For persistence, `chrome.storage.local` stores:
  • User Preferences: Theme, button layout, or decimal precision.
  • Calculation History: Logs recent operations for review.

    • Example Arithmetic Function:
    ```javascript
    function calculate(expression) {
    try {
    // Sanitize input to prevent code injection (e.g., restrict to digits/operators)
    const sanitized = expression.replace(/[^0-9+\-*/.]/g, '');
    return eval(sanitized); // Use a safer alternative (e.g., custom parser) in production
    } catch (error) {
    return "Error";
    }
    }
    ```

    Saving and Retrieving Preferences:
    ```javascript
    // Save theme preference
    chrome.storage.local.set({ theme: 'dark' }, () => {
    document.body.classList.add('dark-mode');
    });

    // Load theme on startup
    chrome.storage.local.get(['theme'], (data) => {
    if (data.theme === 'dark') {
    document.body.classList.add('dark-mode');
    }
    });
    ```

    Security Note:

  • Avoid `eval()` for untrusted input. Implement a whitelist-based parser or library like math.js to handle expressions safely.

    • Testing and Debugging

    Chrome extensions require validation via the Extension Management Page (`chrome://extensions`) and debugging through:
    1. Popup Inspection: Right-click the extension icon → Inspect to debug `popup.html`.
    2. Background Script: Use `chrome.debugger` API or the Service Worker Console (`chrome://inspect/#extensions`).
    3. Storage Verification: Check saved data via:
    ```javascript
    chrome.storage.local.get(null, (data) => {
    console.log('Stored data:', data);
    });
    ```

    Common Issues and Fixes:

  • Manifest Errors: Validate JSON syntax and permissions.
  • Event Listener Failures: Ensure `DOMContentLoaded` wraps interactions.
  • Storage Corruption: Use `chrome.storage.local.clear()` to reset test data.

    • User Experience (UX) and Interface Design for Calculator Chrome Extensions

    The success of a calculator Chrome extension hinges on a seamless user experience (UX) that balances functionality with accessibility and visual appeal. A well-designed interface ensures usability across devices, accommodates diverse user needs, and adheres to modern design principles. Key considerations include responsive layouts, accessibility features like keyboard navigation and screen reader compatibility, and adherence to color contrast guidelines for readability. Additionally, implementing dynamic theming (e.g., dark/light mode) enhances user satisfaction by adapting to environmental preferences and reducing eye strain.

    Effective UX design in calculator extensions prioritizes intuitive interactions, minimal cognitive load, and consistency with user expectations. Below are structured best practices and technical implementations for achieving an optimal interface.

    Responsive Layouts and Adaptive Design

    A responsive calculator interface must function flawlessly across desktop, tablet, and mobile viewports, including Chrome’s extension popup and sidebar constraints. Key strategies include:

    - Fluid Grid Systems: Use relative units (e.g., `rem`, `vw`) and CSS Flexbox/Grid to ensure buttons and input fields scale proportionally without overflow or distortion.

    Example: A calculator with a 4-column button grid on desktop should collapse into a 2-column layout on mobile, with touch targets sized ≥ 48x48px for accessibility.
  • Viewport Meta Tag and Media Queries: Enforce viewport scaling and adjust element spacing, font sizes, and button dimensions using `@media` rules.
    • ```html
    @media (max-width: 400px) {
    .calculator-grid { grid-template-columns: repeat(2, 1fr); }
    .button { min-height: 3.5rem; }
    }
    ```

    - Extension Popup Constraints: Chrome’s popup width is limited to ~300px. Prioritize essential elements (e.g., display, primary buttons) and use tooltips or sidebar panels for secondary functions.

    Accessibility Features for Inclusive Design

    Accessibility ensures the calculator is usable by individuals with disabilities, including visual, motor, or cognitive impairments. Critical implementations include:

    - Keyboard Navigation and Shortcuts:

  • Ensure all interactive elements (buttons, inputs) are focusable via `tabindex` and respond to `Enter`/`Space` key presses.
  • Implement custom keyboard shortcuts (e.g., `Ctrl+1` for memory recall) using the `keydown` event, documented in the extension’s help section.
    • WCAG 2.1 Success Criterion: 2.1.1 Keyboard – All functionality must be operable via keyboard without requiring specific timing.
  • Screen Reader Support:
  • Use ARIA attributes (`aria-label`, `role="button"`) to describe interactive elements.
  • Provide live announcements for dynamic updates (e.g., calculation results) via `aria-live="polite"`.
    • ```html
    0
    ```

    - Color Contrast and Visual Hierarchy:

  • Adhere to WCAG AA contrast ratios (≥4.5:1 for normal text, ≥3:1 for large text) using tools like WebAIM Contrast Checker.
  • Avoid relying solely on color to convey information (e.g., use icons/text alongside red/green for errors/success).

    • Implementing Dark/Light Mode Toggle

    Dynamic theming improves usability by reducing eye strain and adapting to user preferences. Below is a step-by-step guide to integrating a dark/light mode toggle in a calculator extension.

    Step 1: Define CSS Variables for Theming
    Store theme properties in CSS variables to enable easy switching. Use semantic names for maintainability.
    ```css
    :root {
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --text-primary: #333333;
    --text-secondary: #666666;
    --button-bg: #e0e0e0;
    --button-text: #000000;
    --accent-color: #4285f4;
    }

    [data-theme="dark"] {
    --bg-primary: #121212;
    --bg-secondary: #1e1e1e;
    --text-primary: #f0f0f0;
    --text-secondary: #a0a0a0;
    --button-bg: #333333;
    --button-text: #ffffff;
    --accent-color: #8ab4f8;
    }
    ```

    Step 2: Store User Preference in `chrome.storage`
    Persist the theme choice using Chrome’s storage API to survive page reloads.
    ```javascript
    // Save preference
    chrome.storage.local.set({ theme: 'dark' });

    // Load preference on extension startup
    chrome.storage.local.get(['theme'], (data) => {
    const theme = data.theme || 'light';
    document.documentElement.setAttribute('data-theme', theme);
    });
    ```

    Step 3: Implement the Toggle Switch
    Use a checkbox or button to trigger theme changes. Update the DOM and storage synchronously.
    ```html
    ```
    ```javascript
    document.getElementById('theme-switch').addEventListener('change', (e) => {
    const theme = e.target.checked ? 'dark' : 'light';
    document.documentElement.setAttribute('data-theme', theme);
    chrome.storage.local.set({ theme });
    });
    ```

    Step 4: Dynamic Theme Application
    Apply the theme to all elements by referencing CSS variables. For dynamic content (e.g., tooltips), use inline styles or JavaScript.
    ```css
    body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    }

    .button {
    background-color: var(--button-bg);
    color: var(--button-text);
    }
    ```

    Step 5: System Preference Sync (Optional)
    Detect the user’s OS-level theme preference (e.g., `prefers-color-scheme`) and default to it on first launch.
    ```javascript
    if (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) {
    document.documentElement.setAttribute('data-theme', 'dark');
    }
    ```

    Best Practices for Theme Implementation:

  • Performance: Use CSS variables for theme properties to minimize reflows during switching.
  • User Control: Allow users to override the system preference explicitly.
  • Testing: Validate contrast ratios in both themes using automated tools (e.g., axe DevTools).
  • Fallbacks: Provide a default theme if CSS variables are unsupported (e.g., older browsers).

    • calculator chrome extension - Ilustrasi 2

    Advanced Features and Customization in Calculator Chrome Extensions

    Calculator Chrome extensions transcend basic arithmetic by integrating specialized mathematical functions, customizable workflows, and domain-specific applications. Advanced implementations leverage computational libraries to ensure precision, scalability, and real-time processing, while customization options adapt the tool to niche use cases such as financial modeling, engineering simulations, or multi-unit conversions. Performance optimization remains critical to maintain responsiveness, particularly when handling complex operations or large datasets.

    The integration of advanced mathematical functions requires careful selection of libraries to balance accuracy, computational efficiency, and ease of implementation. Below, the focus shifts to technical integration strategies, performance considerations, and innovative applications that extend the utility of calculator extensions beyond conventional boundaries.

    Integration of Advanced Mathematical Functions

    To incorporate functions such as logarithms, exponentials, trigonometric operations, and complex number arithmetic, developers rely on JavaScript libraries designed for numerical computation. math.js stands out as a robust, open-source library that supports symbolic math, unit conversions, and statistical operations while maintaining compatibility with Chrome extensions. Its modular architecture allows selective inclusion of required functions, reducing payload size and improving initialization speed.

    Alternative libraries include:

  • Numeral.js: Optimized for currency and large-number formatting, with built-in support for locale-specific decimal separators.
  • Decimal.js: Ensures high-precision arithmetic, critical for financial or scientific calculations where floating-point rounding errors are unacceptable.
  • Complex.js: Specialized for complex number operations, including polar-to-Cartesian conversions and matrix manipulations.

    • Performance Considerations

  • Lazy Loading: Defer the loading of specialized libraries until their functions are explicitly required, minimizing initial extension startup time.
  • Web Workers: Offload computationally intensive operations (e.g., solving large systems of equations) to background threads to prevent UI freezing.
  • Caching: Store precomputed values (e.g., trigonometric tables or logarithmic constants) to reduce runtime calculations.
  • Precision Trade-offs: Use `BigInt` or `Decimal.js` for high-precision tasks, but default to `Number` for general-purpose operations to balance speed and memory usage.

    • Customization for Domain-Specific Applications

    Calculator extensions can be tailored to address industry-specific needs through configurable inputs, predefined formulas, and unit systems. Below are key customization strategies:

    1. Financial Calculations
    Financial calculators often require support for:

  • Time-value-of-money (TVM): Functions for compound interest, annuity payments, and net present value (NPV).
  • Currency Conversion: Dynamic exchange rate fetching via APIs (e.g., ExchangeRate-API) with historical data logging.
  • Tax and Fee Computations: Customizable tax brackets, VAT calculations, and regulatory adjustments.

    • Example Formula Integration:
    ```javascript
    // Net Present Value (NPV) calculation
    function calculateNPV(cashFlows, discountRate) {
    return cashFlows.reduce((total, cashFlow, year) => total + cashFlow / Math.pow(1 + discountRate, year), 0);
    }
    ```

    2. Engineering and Scientific Workflows
    Engineering calculators may include:

  • Unit Conversions: Comprehensive support for imperial/metric units with precision controls (e.g., 3 decimal places for electrical measurements).
  • Physical Constants: Preloaded values (e.g., Planck’s constant, gravitational acceleration) with SI/USCS toggles.
  • Equation Solvers: Symbolic math for differential equations or root-finding algorithms (e.g., Newton-Raphson).

    • 3. Custom Unit Systems
    Extensions can implement hybrid unit systems (e.g., astronomical units + metric) with:

  • Conversion Chains: Sequential conversions (e.g., miles → kilometers → meters) via user-defined paths.
  • Precision Overrides: Allow users to specify significant digits for intermediate steps (critical in manufacturing or chemistry).
  • Context-Aware Defaults: Auto-select units based on detected input (e.g., "12 in" → inches, "12 cm" → centimeters).

    • Creative Use Cases for Calculator Extensions

    Calculator extensions extend beyond traditional arithmetic through specialized applications that integrate with workflows or external data sources. Below are innovative implementations:
    Real-Time Financial Dashboards
    A calculator extension embedded in a browser could:
  • Pull live stock prices via WebSocket APIs (e.g., Alpha Vantage) and compute moving averages or Bollinger Bands.
  • Simulate portfolio rebalancing with drag-and-drop asset allocation sliders, updating risk metrics dynamically.
  • Generate tax-optimized withdrawal strategies for retirement accounts by cross-referencing with IRS brackets.

    • Engineering Prototyping
    For mechanical or electrical engineers:

  • Circuit Analysis: Solve Kirchhoff’s laws in real-time with interactive schematic inputs, displaying voltage/current distributions.
  • Material Science: Calculate stress-strain relationships using Hooke’s Law with customizable Young’s modulus inputs.
  • Fluid Dynamics: Simulate Bernoulli’s principle for pipe flow scenarios with adjustable pressure gradients.

    • Custom Unit Systems for Niche Industries

  • Astronomy: Convert light-years to parsecs or AU (astronomical units) with built-in speed-of-light constants.
  • Textile Manufacturing: Handle denier (mass per unit length) conversions alongside metric/imperial thread counts.
  • Cooking/Baking: Support volume-to-weight conversions for international recipes (e.g., cups to grams with ingredient-specific densities).
    • Implementation Notes for Creative Features
  • API Integrations: Use Chrome’s `fetch()` with CORS-compliant endpoints (e.g., OpenWeatherMap for environmental calculations).
  • User-Saved Profiles: Store custom formulas or unit presets in `chrome.storage.local` for quick recall.
  • Accessibility: Ensure screen-reader compatibility for formula outputs (e.g., using `aria-labels` for symbolic math).

    • Security, Privacy, and Performance Optimization in Calculator Chrome Extensions

    Calculator Chrome extensions handle sensitive operations, including user input, financial computations, and potential API interactions, necessitating robust security, privacy safeguards, and performance optimizations. Malicious actors may exploit input vulnerabilities to inject scripts or manipulate computations, while inefficient code can degrade user experience and increase resource consumption. Adherence to Chrome Web Store policies ensures compliance and trustworthiness, while performance techniques like lazy-loading and DOM minimization enhance responsiveness. Below are structured approaches to address these critical aspects.

    Security Measures for Calculator Extensions

    Extensions processing user input or external data must implement defense mechanisms to mitigate injection attacks, data leaks, and unauthorized access. Input sanitization prevents malicious payloads (e.g., JavaScript, SQL, or command injection) from executing, while secure storage protocols (e.g., Chrome’s `chrome.storage.local` with encryption) protect sensitive data like API keys. Policy compliance with Chrome’s extension guidelines ensures adherence to data handling restrictions and audit requirements.

    Input Sanitization and Validation
    User-provided inputs in calculator extensions—such as arithmetic expressions, currency values, or unit conversions—can be exploited if not properly validated. Implement the following techniques:

    • Whitelist-Based Filtering
      Restrict input to predefined character sets (e.g., digits, operators, decimal points) using regular expressions. For example, reject inputs containing `