javascript - node.js Callback was already called error -

i need call callback inside recursive function when iterator bigger value or succesfully write requested image file, try , recieve error:

error: callback called.

here code:

async.each(products,  function(product, callback) {             var = products.indexof(product);             var pathnames = pathnormalizer(product.sku + "");              settimeout(                 function () {                     fetchimage(pathnames[0],pathnames[1], 0, 0, function(err){                         console.log("callback"); callback()                     });                 }, 150 * (i + 1) // each progressively wait 150 msec more each             );         }, function(err) {             console.log("async each finish");          }     );  function fetchimage(url, localpath, index, iteration, fetchcallback) {  var extensions = ['jpg', 'png', 'jpeg', 'bmp' , '']; var fileextension; if(extensions[index] === '' ) {     fileextension = extensions[0]; }else{     fileextension = extensions[index]; }  if (iteration > 2 || index === extensions.length) { fetchcallback(null)};    request.get(url + extensions[index], { encoding: null }, function(err,response,body) {     if(err || undefined === response){            settimeout(function(){             console.log('error url : ' + url + extensions[index] + ' ' +  err);             fetchimage(url, localpath, index, iteration,fetchcallback);         }, 200);     }else{         if(response.statuscode === 200) {             fs.writefile('s' + localpath + fileextension, body, 'binary', function(err){    //intentional error here (invalid path)                 if (err){                     settimeout(function(){                         console.log('image saving error : ' + err  + url + extensions[index]);                         fetchimage(url, localpath, index, iteration +1, fetchcallback);                     }, 500);                 }else {                     console.log('image downloaded ' + localpath + fileextension);                 }             });          }else {             fetchimage(url, localpath, index + 1, iteration, fetchcallback);  //try extension         }     } }); } 

there @ least 1 problem in code :

if condition iteration > 2 || index === extensions.length true fetchcallback called 2 times async callback called 2 times.

i suggest change if (iteration > 2 || index === extensions.length) { fetchcallback(null)}; if (iteration > 2 || index === extensions.length) { return fetchcallback(null)};