Error Parsing Xhtml: the Content of Elements Must Consist of Well-Formed Character Data or Markup

Error parsing XHTML: The content of elements must consist of well-formed character data or markup

Facelets is a XML based view technology which uses XHTML+XML to generate HTML output. XML has five special characters which has special treatment by the XML parser:

< the start of a tag.
> the end of a tag.
" the start and end of an attribute value.
' the alternative start and end of an attribute value.
& the start of an entity (which ends with ;).

In case of <, the XML parser is implicitly looking for the tag name and the end tag >. However, in your particular case, you were using < as a JavaScript operator, not as an XML entity. This totally explains the XML parsing error you got:

The content of elements must consist of well-formed character data or markup.

In essence, you're writing JavaScript code in the wrong place, a XML document instead of a JS file, so you should be escaping all XML special characters accordingly. The < must be escaped as <.

So, essentially, the

for (var i = 0; i < length; i++) {

must become

for (var i = 0; i < length; i++) {

to make it XML-valid.

However, this makes the JavaScript code harder to read and maintain. As stated in Mozilla Developer Network's excellent document Writing JavaScript for XHTML, you should be placing the JavaScript code in a character data (CDATA) block. Thus, in JSF terms, that would be:

<h:outputScript>
    <![CDATA[
        // ...
    ]]>
</h:outputScript>

The XML parser will interpret the block's contents as "plain vanilla" character data and not as XML and hence interpret the XML special characters "as-is".

But, much better is to just put the JS code in its own JS file which you include by <script src>, or in JSF terms, the <h:outputScript>.

<h:outputScript name="functions.js" target="head" />

This way you don't need to worry about XML-special characters in your JS code. Additional advantage is that this gives the browser the opportunity to cache the JS file so that average response size is smaller.

javascript error The content of elements must consist of well-formed character data or markup in blogger

see here: Error parsing XHTML: The content of elements must consist of well-formed character data or markup

you may not use a < inside inline scripts because the parser thinks of it to be a tag beginning.

Content of elements must consist of well-formed mark-up

Does this piece of JavaScript happen to live in a <script> tag in an XHTML page? If so, move it to an external JS file, or use a CDATA section in the script tag.

The content of elements must consist of well-formed character data or markup. markup

Sorry, but I guess you have to pass string to document.write(), and also use appendChild() instead of it. I mean, you are trying to do this:

document.write("<script src=\/feeds/posts/default/?max-results=+numposts4+&orderby=published&alt=json-in-script&callback=owlcontent;\><\/script>");

but instead, you can do this (better practise):

let scriptTag = document.createElement("script");
scriptTag.src = "path/to/your/script.js";
document.body.appendChild(scriptTag);

Google analytics experiment causing well-formed character data or markup error

If CDATA doesn't work out, because Google is jerking about it, then there are basically 2 other solutions:

Manually escape XML special characters to make the whole JS code syntactically XML valid. Replace < by <, & by &, > by >, etc.
~~Put JS code in its own JS file and include by <script src>. Not sure if Google Analytics Validator eats that.~~ Edit: thus not.

I'd at least report an issue to Google Analytics guys that their validator is severely broken.

Getting a XHTML parsing error when using JavaScript in Facelets

Try placing the javascript code within a CDATA tag

<script type="text/javascript">
<![CDATA[
$(document).ready(function() {
....
}
]]>
</script>

Error Parsing Xhtml: the Content of Elements Must Consist of Well-Formed Character Data or Markup