userschema pre

UserSchema.pre("save", function(next) {
  var user = this;
  // only hash the password if it has been modified (or is new)
  if (!user.isModified("password")) return next();
  // generate a salt
  bcrypt.genSalt(SALT_WORK_FACTOR, function(err, salt) {
    if (err) return next(err);

    // hash the password using our new salt
    bcrypt.hash(user.password, salt, function(err, hash) {
      if (err) return next(err);

      // override the cleartext password with the hashed one
      user.password = hash;
      next();
    });
  });
});