fix(options): add labelling options for a11y

Provides the option to label slider(s) for screen readers using either a direct label via
`aria-label` or as a reference using `aria-labelledby`.

fixes issue #492

Author: Jason Gill

README.md

@@ -249,7 +249,11 @@ The default options are:
     logScale: false,
     customValueToPosition: null,
     customPositionToValue: null,
-    selectionBarGradient: null
+    selectionBarGradient: null,
+    ariaLabel: null,
+    ariaLabelledBy: null,
+    ariaLabelHigh: null,
+    ariaLabelledByHigh: null
 }
 ````
 
@@ -404,6 +408,10 @@ For custom scales:
 
 **selectionBarGradient** - _Object (default to null)_: Use to display the selection bar as a gradient. The given object must contain `from` and `to` properties which are colors.
 
+**ariaLabel and ariaLabelHigh** - _String (default to null)_: Use to add a label directly to the slider(s) for accessibility. Adds the `aria-label` attribute.
+
+**ariaLabelledBy and ariaLabelledByHigh** - _String (default to null)_: Use instead of ariaLabel and ariaLabelHigh to reference the id of an element which will be used to label the slider(s). Adds the `aria-labelledby` attribute.
+
 ## Change default options
 If you want the change the default options for all the sliders displayed in your application, you can set them using the `RzSliderOptions.options()` method:
 ```js

dist/rzslider.css

@@ -1,7 +1,7 @@
 /*! angularjs-slider - v6.0.2 - 
  (c) Rafal Zajac <[email protected]>, Valentin Hervieu <[email protected]>, Jussi Saarivirta <[email protected]>, Angelin Sirbu <[email protected]> - 
  https://github.com/angular-slider/angularjs-slider - 
- 2017-03-02 */
+ 2017-03-05 */
 /*jslint unparam: true */
 /*global angular: false, console: false, define, module */
 (function(root, factory) {
@@ -81,7 +81,11 @@
       logScale: false,
       customValueToPosition: null,
       customPositionToValue: null,
-      selectionBarGradient: null
+      selectionBarGradient: null,
+      ariaLabel: null,
+      ariaLabelledBy: null,
+      ariaLabelHigh: null,
+      ariaLabelledByHigh: null
     };
     var globalOptions = {};
 
@@ -893,6 +897,10 @@
           this.minH.attr('tabindex', '');
         if (this.options.vertical)
           this.minH.attr('aria-orientation', 'vertical');
+        if (this.options.ariaLabel)
+          this.minH.attr('aria-label', this.options.ariaLabel);
+        else if (this.options.ariaLabelledBy)
+          this.minH.attr('aria-labelledby', this.options.ariaLabelledBy);
 
         if (this.range) {
           this.maxH.attr('role', 'slider');
@@ -902,6 +910,10 @@
             this.maxH.attr('tabindex', '');
           if (this.options.vertical)
             this.maxH.attr('aria-orientation', 'vertical');
+          if (this.options.ariaLabelHigh)
+            this.maxH.attr('aria-label', this.options.ariaLabelHigh);
+          else if (this.options.ariaLabelledByHigh)
+            this.maxH.attr('aria-labelledby', this.options.ariaLabelledByHigh);
         }
       },
 

dist/rzslider.js

@@ -85,7 +85,11 @@
       logScale: false,
       customValueToPosition: null,
       customPositionToValue: null,
-      selectionBarGradient: null
+      selectionBarGradient: null,
+      ariaLabel: null,
+      ariaLabelledBy: null,
+      ariaLabelHigh: null,
+      ariaLabelledByHigh: null
     };
     var globalOptions = {};
 
@@ -897,6 +901,10 @@
           this.minH.attr('tabindex', '');
         if (this.options.vertical)
           this.minH.attr('aria-orientation', 'vertical');
+        if (this.options.ariaLabel)
+          this.minH.attr('aria-label', this.options.ariaLabel);
+        else if (this.options.ariaLabelledBy)
+          this.minH.attr('aria-labelledby', this.options.ariaLabelledBy);
 
         if (this.range) {
           this.maxH.attr('role', 'slider');
@@ -906,6 +914,10 @@
             this.maxH.attr('tabindex', '');
           if (this.options.vertical)
             this.maxH.attr('aria-orientation', 'vertical');
+          if (this.options.ariaLabelHigh)
+            this.maxH.attr('aria-label', this.options.ariaLabelHigh);
+          else if (this.options.ariaLabelledByHigh)
+            this.maxH.attr('aria-labelledby', this.options.ariaLabelledByHigh);
         }
       },
 

dist/rzslider.min.css

@@ -243,6 +243,105 @@
       expect(helper.slider.minH.attr('aria-valuenow')).to.equal('2');
       expect(helper.slider.minH.attr('aria-valuetext')).to.equal('C');
     });
+
+    it('should have labelled single slider when option is set', function() {
+      var sliderConf = {
+        value: 10,
+        options: {
+          floor: 0,
+          ceil: 100,
+          step: 10,
+          ariaLabel: "test label"
+        }
+      };
+      helper.createSlider(sliderConf);
+      expect(helper.slider.minH.attr('aria-label')).to.equal('test label');
+    });
+
+    it('should have labelled range slider when option is set', function() {
+      var sliderConf = {
+        min: 10,
+        max: 90,
+        options: {
+          floor: 0,
+          ceil: 100,
+          step: 10,
+          ariaLabel: "test label",
+          ariaLabelHigh: "test label high"
+        }
+      };
+      helper.createRangeSlider(sliderConf);
+      expect(helper.slider.minH.attr('aria-label')).to.equal('test label');
+      expect(helper.slider.maxH.attr('aria-label')).to.equal('test label high');
+    });
+
+    it('should have labelled by id on single slider when option is set', function() {
+      var sliderConf = {
+        value: 10,
+        options: {
+          floor: 0,
+          ceil: 100,
+          step: 10,
+          ariaLabelledBy: "testId"
+        }
+      };
+      helper.createSlider(sliderConf);
+      expect(helper.slider.minH.attr('aria-labelledby')).to.equal('testId');
+    });
+
+    it('should have labelled by id on range slider when option is set', function() {
+      var sliderConf = {
+        min: 10,
+        max: 90,
+        options: {
+          floor: 0,
+          ceil: 100,
+          step: 10,
+          ariaLabelledBy: "testId",
+          ariaLabelledByHigh: "testIdHigh"
+        }
+      };
+      helper.createRangeSlider(sliderConf);
+      expect(helper.slider.minH.attr('aria-labelledby')).to.equal('testId');
+      expect(helper.slider.maxH.attr('aria-labelledby')).to.equal('testIdHigh');
+    });
+
+    it('should not have labelled by id on single slider when both options set', function() {
+      var sliderConf = {
+        value: 10,
+        options: {
+          floor: 0,
+          ceil: 100,
+          step: 10,
+          ariaLabel: "test label",
+          ariaLabelledBy: "testId"
+        }
+      };
+      helper.createSlider(sliderConf);
+      expect(helper.slider.minH.attr('aria-label')).to.equal('test label');
+      expect(helper.slider.minH.attr('aria-labelledby')).to.equal(undefined);
+    });
+
+    it('should not have labelled by id on range slider when both options set', function() {
+      var sliderConf = {
+        min: 10,
+        max: 90,
+        options: {
+          floor: 0,
+          ceil: 100,
+          step: 10,
+          ariaLabel: "test label",
+          ariaLabelHigh: "test label high",
+          ariaLabelledBy: "testId",
+          ariaLabelledByHigh: "testIdHigh"
+        }
+      };
+      helper.createRangeSlider(sliderConf);
+      expect(helper.slider.minH.attr('aria-label')).to.equal('test label');
+      expect(helper.slider.maxH.attr('aria-label')).to.equal('test label high');
+      expect(helper.slider.minH.attr('aria-labelledby')).to.equal(undefined);
+      expect(helper.slider.maxH.attr('aria-labelledby')).to.equal(undefined);
+    });
   });
 }());