PHP javascript call with PHP variable - php

Question

Good day, I am having a very odd error with my PHP code. I am attempting to dynamically change the content of my webpage by reading from an xml file. I read in some data and assign the data to a PHP variable called $course_title and then attempt to call some Javascript that will update the "innerHTML" of a DOM element. Note: on the line "echo $course_title;' that prints out the correct data to the screen.
$fn = dirname(__FILE__)."/course.xml";
$xml = simplexml_load_file($fn);
$course_bookimagelocation = "";
foreach ($xml->children() as $child)
{
if($child[0]->getName()=="book")
$course_bookimagelocation = $child;
if($child[0]->getName()=="title")
$course_title = $child;
}
//Problems start here...
echo $course_title;
echo '<script type="text/javascript">document.getElementById("heading").innerHTML = "';
echo $course_title;
echo '";</script>';
What is very unique is that the first echo statement prints the correct information, but the next three lines, the .innerHTML does not get changed to that same value. Does anyone know what that is? What is also weird is that if I replace the second "echo '$course_title';" with something like 'Hello world!' then "Hello World!" appears as the innerHTML of the "heading" id object.
EDIT
In the XML file called course.xml, the title element is IC 210 Fall 2010 and the contents of $course_title is IC 210 Fall 2010 so the parsing of the php file appears to be correct and there does not seam to be any special characters like a " or '
I also tried putting everything on the same line and not luck... (I even made sure in the xml file that the <title> element had the text on the same line...

Answer 1

Make sure that .innerHTML = "Some text" are on the same line because .innerHTML = "\nSome Text\n" won't work in javascript.
If you want to have something like this:
.innerHTML = "
Some String
";
try:
.innerHTML = ""+
"Some String" +
"";

Answer 2

"call some Javascript that will update the "innerHTML" of a DOM element." for that we use AJAX, no?
well you can do that way but i think it would be simpler to have the text preloaded in some hidden DIV's and use your functions just to change content's of the DIVS or even toggle visibility of the DIV (as you prefer). That way you will avoid many escaping problem's referred in the comments.
that's the way i would do it if not to use AJAX