getComments(fn, opt_trim) returns an array of all the comments in the specified function.

getComments.js

(function(RGX_COMMENT, RGX_TRIM) {
    getComments = function (fn, opt_trim) {
        var comments = [];
        (fn + '').replace(RGX_COMMENT, function(m, a, b, c) {
            if (!c) {
                m = a == undefined ? b : a;
                comments.push(opt_trim ? m.replace(RGX_TRIM, '') : m);
            }
        });
        return comments;
    };
})(/\/\*([\s\S]*?)\*\/|(?:<\!--|\/\/)([^\r\n]*)|(["'])(?:[^\\\3]+|\\[\s\S])+\3/g, /^[\s\xA0]+|[\s\xA0]+$/g);

The regular expression includes the part for match strings to avoid pulling what looks like a comment out of a string.