Add new option to fix issues with offset dimensions

.gitignore

@@ -0,0 +1,117 @@
+
+# Created by https://www.gitignore.io/api/macos,windows,linux,node
+
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+.AppleDouble
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+
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+
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+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
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README.md

@@ -75,6 +75,25 @@ Although SpatialNavigation is a standalone (pure-javascript-based) library, it c
 
 + [Demonstrations](https://luke-chang.github.io/js-spatial-navigation/demo/)
 
+Deployment
+----------
+
+After changing the source file you can create a new build by entering following line:
+
+```shell
+grunt
+```
+
+This will create a new minified version of the library and saves it into the ``dist`` folder.
+In case you haven't Grunt available yet, just enter 
+
+```shell
+npm install
+```
+
+and Grunt as well as all the needed plugins will be installed in your repository folder. Afterwards you
+can perform the instruction from above to create a new minified version of the library.
+
 Documentation
 -------------
 
@@ -194,7 +213,8 @@ Following is an example with default values.
   leaveFor: null,
   restrict: 'self-first',
   tabIndexIgnoreList: 'a, input, select, textarea, button, iframe, [contentEditable=true]',
-  navigableFilter: null
+  navigableFilter: null,
+  ignoreOffsetDimensionValidation: false
 }
 ```
 
@@ -293,6 +313,15 @@ A callback function that accepts a DOM element as the first argument.
 
 SpatialNavigation calls this function every time when it tries to traverse every single candidate. You can ignore arbitrary elements by returning `false`.
 
+#### `ignoreOffsetDimensionValidation`
+
+  + Type: `'boolean'`
+  + Default: `false`
+
+When the library checks whether an element is navigable or not, it validates the offset width and height values to be greater than zero
+and only then the element is navigable. There're also cases where the offset width and height are zero but the element is still visible and therefore needs to be focusable. 
+In such cases it's possible to disable the validation at all for a particular section or globally.
+
 ### Custom Attributes
 
 SpatialNavigation supports HTML `data-*` attributes as follows:

gruntfile.js

@@ -0,0 +1,32 @@
+const fs = require('fs');
+
+module.exports = function(grunt) 
+{
+    require('jit-grunt')(grunt, {
+        ngtemplates: 'grunt-angular-templates'
+    });
+
+    grunt.initConfig({
+        /**
+         * uglify.
+         */
+        uglify: {
+            options: {
+                beautify: false,
+                preserveComments: 'some',
+                compress: {
+                    drop_console: true
+                }
+            },
+            release: {
+                files: {
+                    'dist/spatial_navigation.min.js': ['src/spatial_navigation.js']
+                }
+            }
+        }
+    });
+
+    grunt.registerTask('default', [
+        'uglify'
+    ]);
+};

package.json

@@ -0,0 +1,29 @@
+{
+  "name": "js-spatial-navigation",
+  "version": "1.0.0",
+  "description": "A javascript-based implementation of Spatial Navigation.",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/exozet/js-spatial-navigation.git"
+  },
+  "keywords": [
+    "spatial",
+    "navigation",
+    "javascript"
+  ],
+  "author": "Luke Chang",
+  "license": "MPL-2.0",
+  "bugs": {
+    "url": "https://github.com/exozet/js-spatial-navigation/issues"
+  },
+  "homepage": "https://github.com/exozet/js-spatial-navigation#readme",
+  "devDependencies": {
+    "grunt": "^1.0.1",
+    "grunt-contrib-uglify": "^2.0.0",
+    "jit-grunt": "^0.10.0"
+  }
+}

spatial_navigation.js → src/spatial_navigation.js

@@ -1,10 +1,10 @@
-/*
+/**
  * A javascript-based implementation of Spatial Navigation.
  *
  * Copyright (c) 2017 Luke Chang.
  * https://github.com/luke-chang/js-spatial-navigation
  *
- * Licensed under the MPL 2.0.
+ * @license Licensed under the MPL 2.0.
  */
 ;(function($) {
   'use strict';
@@ -32,7 +32,20 @@
     restrict: 'self-first', // 'self-first', 'self-only', 'none'
     tabIndexIgnoreList:
       'a, input, select, textarea, button, iframe, [contentEditable=true]',
-    navigableFilter: null
+    navigableFilter: null,
+
+    /**
+     * Disables offset dimension validation.
+     * 
+     * Usually before an element get focused it'll be checked
+     * whether it's navigable or not. To do so it checks, among other things, whether
+     * the offsetWidth or the offsetHeight is greater than null because then it means
+     * that element is visible. Some elements haven't any offsetWidth or offsetHeight 
+     * defined even though they're visible to the viewer. To make those elements 
+     * navigable this option can be set to true and the validation will be ignored. 
+     * That option is available for a particular section or globally.
+     */
+    ignoreOffsetDimensionValidation: false
   };
 
   /*********************/
@@ -518,7 +531,11 @@
         !_sections[sectionId] || _sections[sectionId].disabled) {
       return false;
     }
-    if ((elem.offsetWidth <= 0 && elem.offsetHeight <= 0) ||
+
+    var ignoreOffsetDimensionValidation = (typeof _sections[sectionId].ignoreOffsetDimensionValidation === 'boolean' && _sections[sectionId].ignoreOffsetDimensionValidation === true) ||
+                                        (typeof GlobalConfig.ignoreOffsetDimensionValidation === 'boolean' && GlobalConfig.ignoreOffsetDimensionValidation === true);
+
+    if ((!ignoreOffsetDimensionValidation && elem.offsetWidth <= 0 && elem.offsetHeight <= 0) ||
         elem.hasAttribute('disabled')) {
       return false;
     }