node. JS callback function-blocking versus non-blocking

1. Blocking calls (after reading the file and performing subsequent operations)

var fs = require ("FS");

var data = Fs.readfilesync ('/fs.txt ');

Console.log (Data.tostring ());

Console.log ("program execution ends!");

Output Result:

"File Contents"

"Program execution is over!" ”

2. non-blocking calls (synchronous execution of read files and other operations)

var fs = require ("FS");  

Fs.readfile ('/fs.txt ', function (err,data) {

if (err) return Console.error (ERR);

Console.log (Data.tostring ());

});

Console.log ("program execution ends!");

Output Result:

"Program execution is over!" ”

"File Contents"

node. JS callback function-blocking versus non-blocking