copy double click or triple click selected text to clipboard

copyToClipboard.user.js

// ==UserScript==
// @name         copy-text-to-clipboard
// @version      0.6
// @description  copy the selected text by double click or triple click to clipboard
// @author       mqliutie
// @include      *
// @grant        unsafeWindow
// ==/UserScript==


// example online http://www.mqliutie.com/copy-text-to-clipboard.html
(function () {
    'use strict';
    window.__copy_text_to_clipboard__ = true;
    // window.__copy_text_to_clipboard__ === true;
    // iframe.contentWindow.__copy_text_to_clipboard__ === undefined
    function copyToClipboard(str) {
        const textAreaElement = document.createElement('textarea');
        const iframe = this.__copy_text_to_clipboard__ ? document.createElement('iframe') : textAreaElement;
        iframe.style.display = 'none';
        textAreaElement.value = str;
        document.body.appendChild(iframe);
        if (this.__copy_text_to_clipboard__) {
            iframe.contentDocument.body.append(textAreaElement)
        }
        textAreaElement.select();
        document.execCommand('copy');
        document.body.removeChild(iframe);
    }

    function mouseHandle(event) {
        const detail = event.detail;
        const text = this.getSelection().toString();
        // if the text is empty or click event neither double click nor triple click
        if (!text.trim().length || (detail !== 2 && detail !== 3)) {
            return;
        }
        copyToClipboard.call(this, text)
    }

    // notice the dynamic iframes are not queried
    const iframes = document.querySelectorAll('iframe');

    [...iframes].forEach(iframe => {

        iframe.onload = function () {
            const contentWindow = iframe.contentWindow;
            const contentDocument = iframe.contentDocument;
            // handle iframe copy
            contentDocument.addEventListener('click', mouseHandle.bind(contentWindow));
        }

    })

    document.addEventListener('click', mouseHandle.bind(window));

})();