Accessible alternatives for radioButtons, checkboxGroupInput and fileInput added

inst/js/a11yCheckboxGroupInput.js

@@ -0,0 +1,89 @@
+var a11yCheckboxGroupBinding = new Shiny.InputBinding();
+$.extend(a11yCheckboxGroupBinding, {
+  find: function(scope) {
+    return $(scope).find(".shiny-input-a11ycheckboxgroup");
+  },
+  getValue: function(el) {
+    // Select the checkbox objects that have name equal to the grouping div's id
+    const $objs = $('input:checkbox[name="' + el.id + '"]:checked');
+    const values = new Array($objs.length);
+
+    for (let i = 0; i < $objs.length; i++) {
+      values[i] = $objs[i].value;
+    }
+
+    return values;
+  },
+  setValue: function(el, value) {
+    // Null value should be treated as empty array
+    value = value || [];
+
+    // Clear all checkboxes
+    $('input:checkbox[name="' + el.id + '"]').prop("checked", false);
+
+    // Accept array
+    if (value instanceof Array) {
+      for (let i = 0; i < value.length; i++) {
+        $('input:checkbox[name="' + el.id + '"][value="' + value[i] + '"]')
+          .prop("checked", true);
+      }
+      // Else assume it's a single value
+    } else {
+      $('input:checkbox[name="' + el.id + '"][value="' + value + '"]')
+      .prop("checked", true);
+    }
+  },
+
+  getState: function(el) {
+    const $objs = $('input:checkbox[name="' + el.id + '"]');
+
+    // Store options in an array of objects, each with with value and label
+    const options = new Array($objs.length);
+
+    for (let i = 0; i < options.length; i++) {
+      options[i] = {
+        value: $objs[i].value,
+        label: getLabel($objs[i])
+      };
+    }
+
+    return {
+      label: getLabelNode(el).text(),
+      value: this.getValue(el),
+      options: options,
+    };
+  },
+  receiveMessage: async function(el, data) {
+    const $el = $(el);
+
+    // This will replace all the options
+    if (Object.prototype.hasOwnProperty.call(data, "options") && data["options"] !== undefined) {
+      // Clear existing options and add each new one
+      $el.find("div.shiny-options-group").remove();
+      // Backward compatibility: for HTML generated by shinybootstrap2 package
+      $el.find("label.checkbox").remove();
+      $el.append(data.options);
+      $el.find('.select-all-container').appendTo($el)
+    }
+
+    if (Object.prototype.hasOwnProperty.call(data, "value") && data["value"] !== undefined) {
+      this.setValue(el, data.value);
+    }
+
+    if (Object.prototype.hasOwnProperty.call(data, "label") && data["label"] !== undefined) {
+       await updateLabel(data.label, $el.find("legend"));
+    }
+
+    $(el).trigger("change");
+  },
+  subscribe: function(el, callback) {
+    $(el).on("change.checkboxGroupInputBinding", function () {
+      callback(false);
+    });
+  },
+  unsubscribe: function(el) {
+    $(el).off(".checkboxGroupInputBinding");
+  }
+});
+
+Shiny.inputBindings.register(a11yCheckboxGroupBinding);