The following snippet allows you to add a WYSIWYG field to a Frontend Form that works with Content REST API.
var fieldValue = tinymce.get('yourFieldVelVarName').getContent();
#set($wysiwygField = 'yourFieldVelVarName') <script type="text/javascript" src="/html/js/content/content_form_macro.js"></script> <script src="/html/js/tinymce/js/tinymce/tinymce.js" type="text/javascript"></script> <script type="text/javascript"> tinyMCE.baseURL = "/html/js/tinymce/js/tinymce/"; tinyMCE.init({ mode : "none", theme : "advanced", theme_advanced_blockformats : "p,h1,h2,h3,code", theme_advanced_toolbar_align : "left", theme_advanced_buttons1 : "bold,italic,underline,undo,redo,bullist,numlist,link,separator,formatselect", theme_advanced_buttons2 : "", theme_advanced_buttons3 : "" }); function enableWYSIWYG(textAreaId){ try { tinyMCE.execCommand('mceAddControl', false, textAreaId); }catch(e){ alert(e.message); } enabledWYSIWYG[textAreaId] = true; } </script> <textarea dojoType="dijit.form.Textarea" name="$!{wysiwygField}" id="$!{wysiwygField}" class="textAreaField"> </textarea><span id="alert$!{wysiwygField}" class="errorMessages"></span> <script type="text/javascript"> enableWYSIWYG("$!{wysiwygField}"); </script>