Restore Modal.setAppElement() functionality

Author: evoyy

Diff for: lib/components/Modal.js

@@ -7,12 +7,15 @@ var elementClass = require('element-class');
 var renderSubtreeIntoContainer = require("react-dom").unstable_renderSubtreeIntoContainer;
 
 var SafeHTMLElement = ExecutionEnvironment.canUseDOM ? window.HTMLElement : {};
+var AppElement = ExecutionEnvironment.canUseDOM ? document.body : {appendChild: function() {}};
 
 var Modal = module.exports = React.createClass({
 
   displayName: 'Modal',
   statics: {
-    setAppElement: ariaAppHider.setElement,
+    setAppElement: function(element) {
+        AppElement = ariaAppHider.setElement(element);
+    },
     injectCSS: function() {
       "production" !== process.env.NODE_ENV
         && console.warn('React-Modal: injectCSS has been deprecated ' +
@@ -43,7 +46,7 @@ var Modal = module.exports = React.createClass({
   componentDidMount: function() {
     this.node = document.createElement('div');
     this.node.className = 'ReactModalPortal';
-    document.body.appendChild(this.node);
+    AppElement.appendChild(this.node);
     this.renderPortal(this.props);
   },
 
@@ -53,7 +56,7 @@ var Modal = module.exports = React.createClass({
 
   componentWillUnmount: function() {
     ReactDOM.unmountComponentAtNode(this.node);
-    document.body.removeChild(this.node);
+    AppElement.removeChild(this.node);
   },
 
   renderPortal: function(props) {

Diff for: lib/helpers/ariaAppHider.js

@@ -6,6 +6,7 @@ function setElement(element) {
     element = 'length' in el ? el[0] : el;
   }
   _element = element || _element;
+  return _element;
 }
 
 function hide(appElement) {

Diff for: specs/Modal.spec.js

@@ -30,6 +30,9 @@ describe('Modal', function () {
     var node = document.createElement('div');
     Modal.setAppElement(app);
     ReactDOM.render(React.createElement(Modal, {isOpen: true}), node);
+    var modalParent = app.querySelector('.ReactModalPortal').parentNode;
+    assert.notEqual(modalParent, document.body);
+    assert.equal(modalParent, app);
     equal(app.getAttribute('aria-hidden'), 'true');
     ariaAppHider.resetForTesting();
     ReactDOM.unmountComponentAtNode(node);
@@ -53,6 +56,7 @@ describe('Modal', function () {
         return React.DOM.div({}, React.createElement(Modal, {isOpen: true, ariaHideApp: false}, 'hello'));
       }
     });
+    Modal.setAppElement(document.body);
     ReactDOM.render(React.createElement(App), node);
     var modalParent = document.body.querySelector('.ReactModalPortal').parentNode;
     equal(modalParent, document.body);
@@ -76,6 +80,7 @@ describe('Modal', function () {
     equal(props.closeTimeoutMS, 0);
     ReactDOM.unmountComponentAtNode(node);
     ariaAppHider.resetForTesting();
+    Modal.setAppElement(document.body);  // restore default
   });
 
   it('removes the portal node', function() {