fastclipboard.user.js

// ==UserScript==
// @name         fastclipboard
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @require http://code.jquery.com/jquery-3.4.1.min.js
// @match        *://*/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    var cntrlIsPressed = false;
    $(document).keydown(function(event){
        if(event.which=="17") {
            cntrlIsPressed = true;
        }
    });

    $(document).keyup(function(){
        cntrlIsPressed = false;
    });

    $(document).click(function(e){
        selectMe(e.target,1)
    });

    $('body').append("<style>.elem-to-copy{ border: 2px solid blue; cursor: default; }</style>")
    $('*').hover(function(e){
        if(cntrlIsPressed) {
            $(e.target).addClass('elem-to-copy');
        }
    }, function(e) {
        $(e.target).removeClass('elem-to-copy');
    });

    function selectMe(elem, mouseButton)
    {
        if(cntrlIsPressed)
        {
            switch(mouseButton)
            {
                case 1:
                    console.log("Cntrl +  left click");
                    copyToClipboard($(elem).text().trim())
                    break;
                case 2:
                    console.log("Cntrl + right click");
                    break;
                default:
                    break;
            }
        }


    }

    const copyToClipboard = str => {
        const el = document.createElement('textarea');
        el.value = str;
        el.setAttribute('readonly', '');
        el.style.position = 'absolute';
        el.style.left = '-9999px';
        document.body.appendChild(el);
        el.select();
        document.execCommand('copy');
        document.body.removeChild(el);
    };
})();