Add post written in javascript to demonstrate new js frontmatter capability

pages/2016-12-9-react-component-post/single-date-picker.js

@@ -0,0 +1,41 @@
+import React from 'react';
+
+import SingleDatePicker from 'react-dates/lib/components/SingleDatePicker';
+
+class SingleDatePickerWrapper extends React.Component {
+  constructor(props) {
+    super(props);
+    this.state = {
+      focused: false,
+      date: null,
+    };
+
+    this.onDateChange = this.onDateChange.bind(this);
+    this.onFocusChange = this.onFocusChange.bind(this);
+  }
+
+  onDateChange(date) {
+    this.setState({ date });
+  }
+
+  onFocusChange({ focused }) {
+    this.setState({ focused });
+  }
+
+  render() {
+    const { focused, date } = this.state;
+
+    return (
+      <SingleDatePicker
+        {...this.props}
+        id="date_input"
+        date={date}
+        focused={focused}
+        onDateChange={this.onDateChange}
+        onFocusChange={this.onFocusChange}
+      />
+    );
+  }
+}
+
+export default SingleDatePickerWrapper;