update

js/tiny_mce/plugins/placeholder/plugin.min.js

@@ -0,0 +1,57 @@
+tinymce.PluginManager.add('placeholder', function (editor) {
+  editor.on('init', function () {
+    var label = new Label;
+
+    onBlur();
+
+    tinymce.DOM.bind(label.el, 'click', onFocus);
+    editor.on('focus', onFocus);
+    editor.on('blur', onBlur);
+    editor.on('change', onBlur);
+
+    function onFocus() {
+      label.hide();
+      editor.execCommand('mceFocus', false);
+    }
+
+    function onBlur() {
+      if (editor.getContent() == '') {
+        label.show();
+      } else {
+        label.hide();
+      }
+    }
+  });
+
+  var Label = function () {
+    // Create label el
+    this.text = editor.getElement().getAttribute("placeholder");
+    this.contentAreaContainer = editor.getContentAreaContainer();
+
+    tinymce.DOM.setStyle(this.contentAreaContainer, 'position', 'relative');
+
+    attrs = {
+      style: {
+        position: 'absolute',
+        top: 0,
+        left: 0,
+        bottom: 0,
+        color: '#6c868e',
+        'font-style': 'italic',
+        padding: '1%',
+        width: '98%',
+        overflow: 'hidden',
+        'white-space': 'normal'
+      }
+    };
+    this.el = tinymce.DOM.add(this.contentAreaContainer, "div", attrs, this.text);
+  }
+
+  Label.prototype.hide = function () {
+    tinymce.DOM.setStyle(this.el, 'display', 'none');
+  }
+
+  Label.prototype.show = function () {
+    tinymce.DOM.setStyle(this.el, 'display', '');
+  }
+});