Auto-focus on first textbox

Auto-focuses on the first/main textbox of a site

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(Tôi đã có Trình quản lý tập lệnh người dùng, hãy cài đặt nó!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name        Auto-focus on first textbox
// @namespace   http://userscripts.org/users/23652
// @description Auto-focuses on the first/main textbox of a site
// @include     http://*.youtube.com/*
// @include     https://*.youtube.com/*
// @include     http://*.facebook.com/*
// @include     https://*.facebook.com/*
// @include     http://*
// @include     https://*
// @exclude     file://*
// @copyright   JoeSimmons
// @version     1.0.4
// @license     GPL version 3 or any later version; http://www.gnu.org/copyleft/gpl.html
// @grant       GM_addStyle
// ==/UserScript==

/* CHANGELOG

    1.0.4 (4/30/2015)
        - added a system where it makes sure the textbox is focused, especially for trouble sites like youtube

    1.0.3 (1/30/2015)
        - added some small delays for YouTube for it to work
        - removed the use of JSL; it's unnecessary

*/

(function () {
    'use strict';

    // make sure the page is not in a frame
    if (window.frameElement || window !== window.top) { return; }

    var domain = window.document.domain,
        rDomain = /([a-z0-9]+\.)?([a-z0-9-]+(\.[a-z0-9]+)+)$/,
        site = '',
        delay = 500, // by default, use a fairly slow interval as most sites don't mess with focus too much
        e = document.querySelector('input[type="text"], input[type="search"], textarea'),
        timeStart = Date.now(),
        cancelled = false,
        len, intv;

    function cancel () {
        if (cancelled === false) {
            cancelled = true;
            window.clearInterval(intv);

            window.removeEventListener('keydown', cancel, false);
            window.removeEventListener('mousedown', cancel, false);
            window.removeEventListener('dblclick', cancel, false);
            window.removeEventListener('dragstart', cancel, false);
            window.removeEventListener('scroll', cancel, false);
            window.removeEventListener('unload', cancel, false);
        }
    }

    function doFocus(element, length) {
        var diff = Date.now() - timeStart;

        // don't run this function after user input is detected
        if (cancelled === true) {
            return;
        }

        // focus the text box
        element.focus();

        // highlight its text
        if (length > 0 && typeof element.setSelectionRange === 'function') {
            element.setSelectionRange(length, length);
        }

        // stop focusing if 10 seconds has passed
        if (diff > 9999) {
            cancel();
        }
    }

    // grab the domain minus the subdomain
    if ( domain.match(rDomain) ) {
        site = domain.match(rDomain)[2];
    }

    // this section is for sites that require special attention ;)
    switch (site) {
        case 'youtube.com': {
            // youtube is known to take focus away after it's been focused, so we do it often
            e = document.querySelector('#masthead-search-term');
            delay = 100;
            break;
        }
        case 'userscripts.org': case 'google.com': {
            e = document.querySelector('input[name="q"]');
            break;
        }
        case 'facebook.com': {
            e = document.querySelector('textarea[name="xhpc_message_text"], textarea[name="xhpc_message"]');
            delay = 750;
            break;
        }
    }

    // if the element exists and is visible (in-view), then proceed
    if (e && Math.max(e.offsetWidth, e.offsetHeight) > 0) {
        len = e.value.length;

        if (typeof e.focus === 'function') {
            // keep auto-focusing until the user inputs an action, but not longer than 10 seconds
            intv = window.setInterval(doFocus, delay, e, len);

            window.addEventListener('keydown', cancel, false);
            window.addEventListener('mousedown', cancel, false);
            window.addEventListener('dblclick', cancel, false);
            window.addEventListener('dragstart', cancel, false);
            window.addEventListener('scroll', cancel, false);
            window.addEventListener('unload', cancel, false);
        }
    }
}());