table_click_filter.js

// ==UserScript==
// @name         Table Click Filter
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Click a table cell, filter the column based on input.
// @author       You
// @match        *://*/*
// ==/UserScript==

(function() {
    'use strict';

    function filterColumn(table, columnIndex, filterText) {
        if (!table || !table.rows || table.rows.length === 0) {
            return; // Handle empty or invalid table
        }

        for (let i = 1; i < table.rows.length; i++) { // Start from 1 to skip header
            const row = table.rows[i];
            if (row.cells.length > columnIndex) {
                const cellText = row.cells[columnIndex].innerText;
                if (!(filterText && cellText.indexOf(filterText) === -1)) {
                    row.style.display = 'none';
                }
            }
        }
    }

    function handleCellClick(event) {
        const target = event.target;
        if (target.tagName === 'TD') {
            const cellText = target.innerText;
            const columnIndex = target.cellIndex;
            const table = target.closest('table');

            if (!table) {
                return; // Not in a table
            }

            const userInput = prompt("Filter by:", cellText);

            if (userInput === null) {
                return; // Cancel was pressed
            }

            const filterValue = userInput.trim() === "" ? cellText : userInput.trim();

            filterColumn(table, columnIndex, filterValue);
        }
    }

    document.addEventListener('click', handleCellClick);

})();