js function for exposure django app

exposure.js

            exposure = function () {
                /*
                RETURNS: An exposure URL which returns the specified image resized to specified height and width

                ARGUMENTS: object || url:string [, height:string||int] [, width:string||int]
                The exposure method takes either an object or one or more strings as arguments.

                A value of "0" for "width" or "height" indicates that exposure should use a value
                that maintains the image's native aspect ratio.

                USAGE:
                exposure( { url: 'http://mydomain.com/path/to/image.jpg'[, width: #] [, height: #] } )
                exposure( { url: 'http://mydomain.com/path/to/image.jpg', width: 100, height: 0 } )
                If an object is passed, it must contain at least a "url" key with
                it's value being the fully qualified URL of the image to be resized. Optionally,
                "width" and "height" keys may also be included.

                exposure( url, [width,] [height])
                exposure( url, 600, 400)
                If strings are passed, the only required argument is "url" which must be the fully
                qualified url for the image that is to be resized.
                */
                var url, width, height, errorMsg;

                url = arguments[0];
                width = arguments[1] || 0;
                height = arguments[2] || 0;

                errorMsg = 'exposure(): a fully qualified url for an image must be supplied';

                if (url) {
                    if (url['url']) {
                        width = url['width'] || 0;
                        height = url['height'] || 0;
                        url = url['url'];
                    }
                    if (typeof url !== 'string') {
                        throw new Error(errorMsg);
                    } else {
                        return ['/exposure/transcode/', width, '/', height, '/?url=', url].join();
                    }
                } else {
                    throw new Error(errorMsg);
                }
            };