I am trying to store the hash password and checking the it is valid or not.
var bcrypt = require('bcrypt'); let data = ""; bcrypt.genSalt(10, function(err, salt) { bcrypt.hash("my password", salt, function(err, hash) { // Store hash in your password DB. console.log(hash); data = hash; }); }); bcrypt.compare("my password", data, function(err, res) { // res === true console.log(res) }); return value always false.?
but if I move the compare inside genSalt function its returning true.
Thanks
You are dealing with asynchronous functions in node.js, so this result is expected. For the clearer understanding of the problem try to console.log data before bcrypt.compare. I can certainly say it would be equal to an initial value of "".
Then try to move your compare function inside the .hash callback
var bcrypt = require('bcrypt'); let data = ""; bcrypt.genSalt(10, function(err, salt) { bcrypt.hash("my password", salt, function(err, hash) { // Store hash in your password DB. console.log(hash); data = hash; console.log(data); // Here data equals to your hash bcrypt.compare("my password", data, function(err, res) { // res === true console.log(res) }); }); }); console.log('data') // Here data equals to initial value of "" You can use async/await functions to make it look like synchronous code and get rid of callbacks. Luckily, bcrypt support promise interface that is used by async/await
const salt = await bcrypt.genSalt(10); const hash = await bcrypt.hash("my password", salt); const result = await bcrypt.compare("my password", data); console.log(result); 
bcrypt.compareSync be used here?
async / await to the ES7 specification.
data === "". Possible duplicate of Why is my variable unaltered after I modify it inside of a function? - Asynchronous code reference