javascript - Response whose "body" is locked cannot be used to respond to a request -

i trying service workers in google chrome. stumbled upon error. googling error gives 1 single result @ moment seems in google chrome sourcecode.

i not convinced error bug. when try in firefox, corrupted content error screen. occurs when handling fetch event project root:

self.addeventlistener('fetch', function(event) {   // nice url   var requesturl = new url(event.request.url);   console.log("request for: ", requesturl.href);   // network, cache, fallback   event.respondwith(     // try download     fetch(event.request)       .then(function(x) {         console.log("    "+requesturl.href+" >> ",x);         // if failed x not ok         if(x && x.ok) {           // if result ok save cache           cache.put(event.request, x);           return x;         }         else           // try fetch cached version if request failed           return cache.match(event.request);       })       // in case of error return 404 page       .catch(function(error) {         console.warn("    "+requesturl.href+" >> unavailable: ",error);         return cache.match('/page/content-not-available-offline');       })   ); }); 

i'm not sure body locked error means, don't know code relevant.

the problem body of response (the actual content, such html or javascript) can used once purposes, such saving cache or using actual response.

to solve this, response.prototype.clone() method exists.

in fact, main reason clone() exists allow multiple uses of body objects (when one-use only.)

in case, problem storing response in cache , returning it. correct approach is:

if(x && x.ok) {   // if result ok save cache   cache.put(event.request, x.clone());   return x; }