Make safe relation ids in environment view

app/views/utils.js

Index: app/views/utils.js
=== modified file 'app/views/utils.js'
--- app/views/utils.js	2013-04-10 09:40:06 +0000
+++ app/views/utils.js	2013-04-10 21:17:18 +0000
@@ -12,6 +12,41 @@
   var views = Y.namespace('juju.views'),
       utils = Y.namespace('juju.views.utils');
 
+  /*jshint bitwise: false*/
+  /**
+    Create a hash of a string. From stackoverflow: http://goo.gl/PEOgF
+
+    @method generateHash
+    @param {String} value The string to hash.
+    @return {Integer} The hash of the string.
+   */
+  var generateHash = function(value) {
+    return value.split('').reduce(
+        function(hash, character) {
+          hash = ((hash << 5) - hash) + character.charCodeAt(0);
+          return hash & hash;
+        },
+        0
+    );
+  };
+  /*jshint bitwise: true*/
+  utils.generateHash = generateHash;
+
+  /**
+    Create a stable, safe DOM id given an arbitrary string.
+    See details and discussion in
+    https://bugs.launchpad.net/juju-gui/+bug/1167295
+
+    @method generateSafeDOMId
+    @param {String} value The string to hash.
+    @return {String} The calculated DOM id.
+   */
+  var generateSafeDOMId = function(value) {
+    return (
+        value.replace(/\W/g, '_') + '-' + generateHash(value));

[benji, 2013/04/11 12:39:44]

If value starts with a number then the result will still start with a number,
which is not valid.  A constant prefix of one of _, -, or a-z would fix that.

Subliminal message: dashes are prettier than underscores.

[benji, 2013/04/11 13:16:53]

I just realized that there is another small issue with using \W: it doesn't
include the dash character, so dashes will unnecessarily be transformed into
underscores.

I would use an inverted character class instead of \W, [^-a-zA-Z0-9] in
particular.

+  };
+  utils.generateSafeDOMId = generateSafeDOMId;
+
   var timestrings = {
     prefixAgo: null,
     prefixFromNow: null,