javascript - Callbacks within Streams on('data') and on('end') and Mongoose.js -

i reading large .csv file using fast-csv

myfile.js

var count = 0; var stream = fs.createreadstream("name of file"); fcsv(stream)   .on('data', function(data) {     modelname.find(query, function(err, docs) {       console.log('docs', docs);       count = count++;     });   })   .on('end', function() {     console.log('done', count);   })   .parse(); 

the script runs , list of docs printed out , on('end') triggered.

how count value print out number of docs? prints out 0.

any suggestions?

you mixed 2 different styles count variable. see lets @ little example.

var cnt = 0 (var = 0; < 10; i++) {     cnt = cnt++ //<-- bug right here }; console.log(cnt) 

what happens cnt on right side being incremented not assigned left cnt. reason cnt++ post-incremental , increase happpens after line of code has been completed , therefore after assignment left cnt.

to see full extent @ second example.

var lines = [] lines[0] = 0 (var = 0; < 10; i++) {     lines[i+1] = lines[i]++ //<-- bug (again) right here     console.log("lines[" +    + "] = " + lines[i] +             " \t lines["+ (i+1) + "] = " + lines[i+1]) }; 

here create empty list lines , fill next array position lines[i+1] number current position. current position being post-incremented. you can see in output number of previous array position 1 , number of next 0.

what want write instead of these:

• cnt = ++cnt
• cnt = cnt + 1
• cnt++
• cnt += 1