initial setup for editor page to generate graph through textarea input

src/editor.js

@@ -0,0 +1,47 @@
+function decodeHTMLEntities (str) {
+    if(str && typeof str === 'string') {
+      // strip script/html tags
+      element = document.querySelector('.editor');
+        
+      str = str.replace(/<script[^>]*>([\S\s]*?)<\/script>/gmi, '');
+      str = str.replace(/<\/?\w(?:[^"'>]|"[^"]*"|'[^']*')*>/gmi, '');
+      element.innerHTML = str;
+      str = element.textContent;
+      element.textContent = '';
+    }
+
+    return str;
+}
+
+var mermaidEditor =  {
+    $ : document.querySelector,
+    textField : '',
+    submit : '',
+    graph : '',
+
+    init: function () {
+
+        document.querySelector('.button').addEventListener('click', function () {
+            mermaidEditor.update();
+        }.bind(this));
+    },
+    
+    update: function () {
+        var txt = document.querySelector('.editor').value;
+        txt = txt.replace(/>/g,'&gt;');
+        txt = txt.replace(/</g,'&lt;');
+        txt = decodeHTMLEntities(txt).trim();
+
+        document.querySelector('.mermaid').innerHTML = txt;
+        mermaid.init();
+        document.querySelector('.editor').value = txt;
+    }
+};
+
+document.addEventListener('DOMContentLoaded', function () {
+
+    mermaidEditor.init();
+
+}, false);
+
+exports = mermaidEditor;