libClient/level1_http.js
function() {
            if (xhr.readyState === 4 && xhr.status === 200) {
                return cb(null, JSON.parse(xhr.response));
            }
            cb('error requesting ' + uri);
        }
function() {
            if (xhr.readyState === 4 && xhr.status === 200) {
                return cb(null, JSON.parse(xhr.response));
            }
            cb('error requesting ' + uri);
        }
function ( ) { if ( xhr . readyState === 4 && xhr . status === 200 ) { return cb ( null , JSON . parse ( xhr . response ) ) ; } cb ( 'error requesting ' + uri ) ; }
setup callback to handle result
setup callback to handle result