asynchronous - using async.js with node.js streams -

i want use asyn.js limiting number of parallel io operations. have come across following example:

async.foreachlimit items, 5, ((item, next) ->   request item.url, (error, response, body) ->     console.log body     next error)     , (err) ->         throw err  if err         console.log "all requests processed!" 

but want use streams, this:

async.foreachlimit items, 5, ((item, next)->     stream = fs.createwritestream file     request.get(item.url).pipe(stream))     , (err)->           throw err  if err           console.log "all requests processed!" 

how place 'next' call when writestream done writing file?

you'll need bind readable stream's 'end' event separate .pipe().

res = request.get(item.url) res.pipe(stream) res.on 'end', next 

this lets bind 'error' event:

res.on 'error', next 

but, listen writable stream's 'finish' event:

request.get(item.url)     .on 'finish', next