mdw@git.distorted.org.uk Git - chopwood/blob - chpwd.js

   1 /* -*-js-*-
   2  *
   3  * Common JavaScript code for Chopwood
   4  *
   5  * (c) 2013 Mark Wooding
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Chopwood: a password-changing service.
  11  *
  12  * Chopwood is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Affero General Public License as
  14  * published by the Free Software Foundation; either version 3 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Chopwood is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Affero General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Affero General Public
  23  * License along with Chopwood; if not, see
  24  * <http://www.gnu.org/licenses/>.
  25  */
  26
  27 /*----- Some utilities ----------------------------------------------------*/
  28
  29 function elt(id) {
  30   /* Return the element with the requested ID. */
  31   return document.getElementById(id);
  32 }
  33
  34 function map(func, list) {
  35   /* Apply FUNC to each element of LIST, which may actually be any object;
  36    * return a new object mapping the same keys to the images of the values in
  37    * the function FUNC.
  38    */
  39   var i;
  40   var out = {};
  41   for (i in list) out[i] = func(list[i]);
  42   return out;
  43 }
  44
  45 /*----- Form validation ---------------------------------------------------*/
  46
  47 var FORMS = {};
  48 /* A map of form names to information about them.  Each form is an object
  49  * with the following slots:
  50  *
  51  *   * elts: A list of element-ids for the form widgets.  These widgets will
  52  *     be checked periodically to see whether the input data is acceptable.
  53  *
  54  *   * check: A function of no arguments, which returns either `null' if
  55  *     everything is OK, or an error message as a string.
  56  *
  57  * Form names aren't just for show.  Some element-ids are constructed using
  58  * the form name as a base:
  59  *
  60  *   * FORM-whinge: An output element in which to display an error message if
  61  *     the form's input is unacceptable.
  62  *
  63  *   * FORM-submit: The Submit button, which needs hooking to inhibit
  64  *     submitting a form with invalid data.
  65  */
  66
  67 function update(obj, slot, value) {
  68   /* Update an object slot only if we're gping to change its value. */
  69   if (obj[slot] !== value) obj[slot] = value;
  70 }
  71
  72 function check() {
  73   /* Check through the various forms to make sure they're filled in OK.  If
  74    * not, set the `F-whinge' elements, and disable `F-submit'.
  75    */
  76   var f, form, whinge;
  77
  78   for (f in FORMS) {
  79     form = FORMS[f];
  80     we = elt(f + '-whinge');
  81     sb = elt(f + '-submit');
  82     whinge = form.check();
  83     if (sb !== null) update(sb, 'disabled', whinge !== null);
  84     if (we !== null) {
  85       update(we, 'textContent', whinge || 'OK');
  86       update(we, 'className',  whinge === null ? 'whinge' : 'whinge wrong');
  87     }
  88   }
  89
  90   // We can't catch all possible change events: in particular, it seems
  91   // really hard to capture changes as a result of selections from a menu --
  92   // e.g., delete or paste.  Accept this, and just recheck periodically.
  93   check_again(1000);
  94 }
  95
  96 var timer = null;
  97 /* The timer for the periodic validation job. */
  98
  99 function check_again(when) {
 100   /* Arrange to check the forms again in WHEN milliseconds. */
 101   if (timer !== null) clearTimeout(timer);
 102   timer = setTimeout(check, when);
 103 }
 104
 105 var Q = 0;
 106 function check_soon(ev) {
 107   /* Arrange to check the forms again very soon. */
 108   check_again(50);
 109 }
 110
 111 function check_presubmit(ev, f) {
 112   /* Check the form F now, popping up an alert and preventing the event EV if
 113    * there's something wrong.
 114    */
 115   var whinge = FORMS[f].check();
 116
 117   if (whinge !== null) {
 118     ev.preventDefault();
 119     alert(whinge);
 120   }
 121 }
 122
 123 function init() {
 124   /* Attach event handlers to the various widgets so that we can keep track
 125    * of how well things are being filled in.
 126    */
 127   var f, form, w, e;
 128
 129   // Start watching for changes.
 130   check_soon();
 131
 132   for (f in FORMS) (function (f, form) {
 133
 134     // Ugh.  We have to lambda-bind `f' here so that we can close over it
 135     // properly.
 136     for (w in form.elts) {
 137       if ((e = elt(f + '-' + form.elts[w])) === null) continue;
 138       e.addEventListener('click', check_soon, false);
 139       e.addEventListener('change', check_soon, false);
 140       e.addEventListener('keypress', check_soon, false);
 141       e.addEventListener('blur', check_soon, false);
 142     }
 143     if ((e = elt(f + '-submit')) !== null) {
 144       e.addEventListener('click', function (ev) {
 145         return check_presubmit(ev, f)
 146       }, false);
 147     }
 148   })(f, FORMS[f]);
 149 }
 150
 151 window.addEventListener('load', init, false);
 152
 153 /*----- That's all, folks -------------------------------------------------*/