[TSC-9] Add numeric input validator module

- Create validator.js with validateNumericInput() function - Validates numeric strings; allows digits, leading minus, single decimal point - Rejects invalid characters, multiple decimals, misplaced minus signs - Returns { isValid, value, sanitized } object - Link validator.js in index.html <head> - Update CLAUDE.md project structure to include validator.js
2026-07-08 07:58:12 +00:00
3 changed files with 49 additions and 0 deletions
--- a/CLAUDE.md
+++ b/CLAUDE.md
@ -8,6 +8,7 @@ Greenfield project. Implementation is driven by the Vexa AI-SDLC pipeline (Jira
 /
 ├── index.html  # Calculator UI (semantic HTML5)
 ├── styles.css  # Responsive CSS layout and styling
 ├── validator.js  # Numeric input validator (validateNumericInput)
 ├── README.md   # Project overview
 └── CLAUDE.md   # This file
 ```
--- a/index.html
+++ b/index.html
@ -5,6 +5,7 @@
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Simple Calculator</title>
  <link rel="stylesheet" href="styles.css">
  <script src="validator.js"></script>
 </head>
 <body>
  <main>
--- a/validator.js
+++ b/validator.js
@ -0,0 +1,47 @@
 /**
 * Validates a numeric input string.
 *
 * Allowed characters: digits 0-9, a single decimal point, a leading minus sign.
 * Returns an object with:
 *   isValid  {boolean} - true when the string represents a well-formed number
 *   value    {number|null} - parsed numeric value, or null when invalid
 *   sanitized {string} - trimmed input string
 */
 function validateNumericInput(input) {
  var str = String(input).trim();
  var result = { isValid: false, value: null, sanitized: str };
  if (str === '') {
    return result;
  }
  // Reject characters other than digits, decimal point, and minus sign
  if (/[^0-9.\-]/.test(str)) {
    return result;
  }
  // Minus sign is only valid as the very first character
  var minusCount = (str.match(/-/g) || []).length;
  if (minusCount > 1 || (minusCount === 1 && str.charAt(0) !== '-')) {
    return result;
  }
  // Only one decimal point is allowed
  if ((str.match(/\./g) || []).length > 1) {
    return result;
  }
  // A bare '-' or '.' is not a valid number
  if (str === '-' || str === '.') {
    return result;
  }
  var parsed = parseFloat(str);
  if (isNaN(parsed)) {
    return result;
  }
  result.isValid = true;
  result.value = parsed;
  return result;
 }