Right now we use codemirror's JavaScript mode on the website but there's a JSX mode now so we should start using that instead.

var d = {};
    var input = d.input = elt("textarea", null, null, "position: absolute; padding: 0; width: 1px; height: 1em; outline: none; font-size: 4px;");
    if (webkit) input.style.width = "1000px";
    else input.setAttribute("wrap", "off");
    
    if (ios) input.style.border = "1px solid black";
    input.setAttribute("autocorrect", "off"); input.setAttribute("autocapitalize", "off"); input.setAttribute("spellcheck", "false");
    
    d.inputDiv = elt("div", [input], null, "overflow: hidden; position: relative; width: 3px; height: 0px;");
    
    d.scrollbarH = elt("div", [elt("div", null, null, "height: 1px")], "CodeMirror-hscrollbar");
    d.scrollbarV = elt("div", [elt("div", null, null, "width: 1px")], "CodeMirror-vscrollbar");
    d.scrollbarFiller = elt("div", null, "CodeMirror-scrollbar-filler");
    d.gutterFiller = elt("div", null, "CodeMirror-gutter-filler");
    
    d.lineDiv = elt("div", null, "CodeMirror-code");
    d.selectionDiv = elt("div", null, null, "position: relative; z-index: 1");
    
    d.cursor = elt("div", "\u00a0", "CodeMirror-cursor");
    
    d.otherCursor = elt("div", "\u00a0", "CodeMirror-cursor CodeMirror-secondarycursor");
    
    d.measure = elt("div", null, "CodeMirror-measure");
    
    d.lineSpace = elt("div", [d.measure, d.selectionDiv, d.lineDiv, d.cursor, d.otherCursor],
                         null, "position: relative; outline: none");