javascript - node.js large number of requests throwing error -

i got troubles image downloader script, have array images names (size around 5000 elements), , cycle in array, , every iteration download image requests module.

all works fine have arrays size not bigger 500+- elements.

if run script 5000+ elements, see many errors spamed request module(err or underfined responce object) , , finnaly application fails empty file error. think there async troubles cause node.js didnt handles many operation @ time.

maybe can solve splitting large 5000 size array 300 items, , dont iterate over(and dont call fetchimage()) on next chunck before previous chunk. or maybe there exists more nicer way solving problem.?

products.map(function (product) {         fetchimage(product.imageurl,'./static/' + product.filename + '_big.', 0, 0);         return;     });  function fetchimage(url, localpath, index, iteration) {     var extensions = ['jpg', 'png', 'jpeg', 'bmp' , ''];      if (iteration > 2 || index === extensions.length) { // try extensions         iteration++;         if(iteration < 3) {             settimeout(function(){                 fetchimage(url, localpath, 0, iteration);             }, 3000);         }else{             console.log('fetching ' + url + ' failed or no image exists ');             return;         }         return;     }      var fileextension;      if(extensions[index] === '' ) {         fileextension = extensions[0];     }else{         fileextension = extensions[index];     }      request.get(url + extensions[index], function(err,response,body) {          if(err || undefined === response){   // if err try after 3 sec timeout             settimeout(function(){                 console.log('error url : ' + url + extensions[index]);                 fetchimage(url, localpath, index, iteration);             }, 3000);             return;         }else{             if(response.statuscode === 200) {                 request(url + extensions[index])                                       .on('error', function(err) {                         console.log("errrrrror " + url + extensions[index] + " " + err);                         settimeout(function(){                             console.log('error url : ' + url + extensions[index]);                             fetchimage(url, localpath, index, iteration);                         }, 3000);                         return;                     })                     .pipe(fs.createwritestream(localpath + fileextension ));// write image file                  console.log('successfully downloaded file ' + localpath + fileextension);                 return;             }else {                 fetchimage(url, localpath, index + 1, iteration);             }         }     }); }; 

fixed using settimeout beetween each request

settimeout(             function () {                 fetchimage(imageurl,'./static/' + filename + '_big.', 0, 0);             },                 300 * (i + 1) // each progressively wait 300 msec more each         );