Form Validations Node.js

You can do it custom validators of mongoose: https://mongoosejs.com/docs/validation.html#custom-validators For example, if you want your password to contain only numbers(using RegEx):

const Schema = mongoose.Schema;
const userSchema = new Schema({
  Username: {
    type: String,
    required: true
  },
  Password: {
    type: String,
    required: true,
    validate: {
       validator: function(v) {
          return /^[0-9]*$/gm.test(v); // this is RegEx of validation only numbers : https://www.regextester.com/21
       },
       message: props => `${props.value} should be a number!`
    },
  }
});

userSchema.pre('save', async function (next) {
  try {
    const user = this;

    if (!user.isModified('Password')) {
      next();

    }

    const salt = await bcrypt.genSalt(10);
    const passwordHash = await bcrypt.hash(this.Password, salt);
    this.Password = passwordHash;
    next();
  } catch (error) {
    next(error);
  }
});


module.exports = User;```