Auto copy selected text

auto-copy.user.js

// ==UserScript==
// @name     auto-copy
// @include  *
// @grant    GM_setClipboard
// ==/UserScript==

function getSelectedText() {
    // console.log(getSelection().anchorNode.nodeName);
    if (window.getSelection().anchorNode.nodeName== "#text") {
        return window.getSelection().toString();
    }
    return false;
}

function doSomethingWithSelectedText() {
    var selectedText = getSelectedText();
    if (selectedText) {
        GM_setClipboard (selectedText);
    }
}

document.onmouseup = doSomethingWithSelectedText;