https://photozou.jp/js/autofocus.js

1/**
2 * autofocus.js
3 * Copyright (c) 2006 Unoh Inc. (http://unoh.net)
4 * ---
5 * USES:
6 *   <script type="text/javascript" src="/js/prototype.js"></script>
7 *   <script type="text/javascript" src="/js/autofocus.js"></script>
8 * ---
9 */
10
11var AutoFocus = {
12    Version: '1.0.0',
13    checkCanFocus: function () {
14	frms = AutoFocus._getTags('form');
15        for (var i = 0; i < frms.length; i++) {
16            var frm = frms[i];
17            if (!frm.childNodes) continue;
18            AutoFocus._checkCanFocus(frm);
19        }
20    },
21    _getTags: function (tagName) {
22        var o;
23	o = document.getElementsByTagName(tagName);
24        return o;
25    },
26    _checkCanFocus: function (obj) {
27        // check childNodes
28        if (obj.childNodes) {
29            var ns = obj.childNodes;
30            for (var i = 0; i < ns.length; i++) {
31                var cn = ns[i];
32                if (AutoFocus._checkCanFocus(cn)) return true;
33            }
34        }
35        // check this node
36        if (!obj.nodeName) return false;
37        if (obj.nodeName == "INPUT") {
38            if (obj.type == "text" || obj.type == "search" || obj.type == "radio" || obj.type == "checkbox" || obj.type == "email" || obj.type == "password") {
39                obj.focus();
40                return true;
41            }
42        }
43        if (obj.nodeName == "TEXTAREA") {
44            obj.focus();
45            return true;
46        }
47        return false;
48    }
49};
50
51// add onLoad event
52Event.observe(window, 'load', AutoFocus.checkCanFocus, false);
53