Transform HTML table into JSON data.

table-to-json.js

/**
 * Transforms HTML table into JSON data.
 * 
 * Sample input:
 * 
 * <table>
 *   <thead>
 *     <tr>
 *       <th>Heading 1</th>
 *       <th>Heading 2</th>
 *     </tr>
 *   </thead>
 *   <tbody>
 *     <tr>
 *       <td>Value 1a</td>
 *       <td>Value 2a</td>
 *     </tr>
 *     <tr>
 *       <td>Value 1b</td>
 *       <td>Value 2b</td>
 *     </tr>
 *   </tbody>
 * </table>
 * 
 * Sample output:
 * 
 * [
 *   { 'Heading 1': 'Value 1a', 'Heading 2': 'Value 2a' },
 *   { 'Heading 1': 'Value 1b', 'Heading 2': 'Value 2b' }
 * ]
 * 
 * @param {HTMLTableElement} table 
 */
function tableToJSON(table) {
  const headers = Array.from(table.querySelectorAll('thead tr th')).map(el => el.textContent.trim());
  const result = [];
  const rows = Array.from(table.querySelectorAll('tbody tr'));
  rows.forEach(row => {
    const cells = Array.from(row.querySelectorAll('td')).map(el => el.textContent.trim());
    result.push(headers.reduce((rowRes, header, headerIndex) => {
      return {
        ...rowRes,
        [header]: cells[headerIndex]
      };
    }, {}));
  });
  return result;
}