Comments should make it fairly straightforward to accomplish:

function foo() {

/* ...characters for image data... /

bar();

/ ...more image data... */

The asterisks are not showing up but you get the idea. It checks out with the comments part of the javascript spec as well:

http://ecma-international.org/ecma-262/5.1/#sec-7.4

...as the text inside the comment can be any unicode code unit except for an asterisk (For source Character rules see http://ecma-international.org/ecma-262/5.1/#sec-6).