CodeMirror HTML mode not working

Question

CodeMirror parses HTML using the XML mode. To use it, the appropriate script must be included, same as with any other mode.

Add its dependency in your markup:

<script type="text/javascript" 
        src="https://stackoverflow.com/site.com/js/libs/codemirror/mode/xml/xml.js"></script>

and set the mode to xml:

config = {
    mode : "xml",
    // ...
};

In addition, you may want to configure the parser to allow for non well-formed XML. You can do so by switching the htmlMode flag on:

config = {
    mode : "xml",
    htmlMode: true,
    // ...
};

See the XML/HTML mode demo for a live example.