First of all, it should be noted that this has nothing to do with javascript. You could have any form of text. Your actual question is how to use a variable inside of a heredoc.
Heredoc is defined as the following:
Nowdocs are to single-quoted strings what heredocs are to double-quoted strings. A nowdoc is specified similarly to a heredoc, but no parsing is done inside a nowdoc. The construct is ideal for embedding PHP code or other large blocks of text without the need for escaping.
Meaning that since this works:
$name = 'Foo';
echo "My name is $name"; // Using double quotes so variables get expanded
Then this also works:
$name = 'Foo';
echo <<$name
EOD; // Using heredoc so variables get expanded
Essentially meaning that yes, as long as you put your 'Do stuff' content into a variable first. Note that if you use more advanced variables/arrays, it's a good idea to do a $array = json_encode($array) before pasting it into JS code (imagine if $name was The Boss's Wife - then the apostrophe would ruin your JS if you don't encode it).
DEMO
