Error parsing XHTML: The content of elements must consist of well-formed character data or markup
As an extension of this question, I'm trying to insert Javascript to a <h:commandButton />'s onclick property as action is already rendering an ajax table.
What I want to do:
Get the selected items in a list box and turn them into parameters to be used in a JSF FileServlet. i.e. para2=value1¶m=value2¶m=value3
Here's what I have:
<script type ="text/javascript">
function myScript() {
var box = document.getElementbyId('myForm:box');
var length = box.options.length;
var paramstring = "";
for (var i = 0; i < length; i++) {
if (i != (length - 1) {
if (box.options[i].selected) {
paramstring = paramstring + "param=" + box.options[i].value + "&";
}
} else {
paramstring = paramstring + "param=" + box.options[i].value;
}
}
if (document.getElementById('myForm:checkbox').checked) {
window.location='fileServlet? + paramstring;
}
}
</script>
What I get when page is loaded:
javax.servlet.ServletException: Error Parsing /page.xhtml: Error Traced[line:15] The content of elements must consist of well-formed character data or markup.
What doesn't trigger exception:
<script type ="text/javascript">
function myScript() {
var box = document.getElementbyId('myForm:box');
var length = box.options.length;
var paramstring = "";
if (document.getElementById('myForm:checkbox').checked) {
window.location='fileServlet? + paramstring;
}
}
</script>
As soon as I add in for (var i = 0; i < length; i++) or even for (var i = 0; i < 10; i++) the page wouldn't load. Why does it not like the for loop?
Answer
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 was 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.