Validation.js

export class Validation {
  constructor(data, emptyFieldErrorMesage) {
    this.data = data;
    this.hasErrors = false;
    this.errors = {};
    this.emptyFieldErrorMesage = emptyFieldErrorMesage;
  }

  startValidation() {
    return this;
  }

  validateEmptyFields() {
    Object.keys(this.data).forEach((field) => {
      if (!this.data[field].trim()) {
        this.errors = {
          ...this.errors,
          [field]: {
            message: this.emptyFieldErrorMesage,
          },
        };
      }
    });
    return this;
  }

  validateEmail() {
    const emailRegex =
      /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$/;
    if (this.data.email) {
      if (!this.data.email.match(emailRegex)) {
        this.errors = {
          ...this.errors,
          email: {
            message: "Please provide a valid email",
          },
        };
      }
    }
    return this;
  }

  validatePassword() {
    const passwordRegex =
      /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$/;
    if (this.data.password) {
      if (!this.data.password.match(passwordRegex)) {
        this.errors = {
          ...this.errors,
          password: {
            message:
              "Password should be minimum 8 characters long with atleast one uppercase ,one lowercase, one number and one special character",
          },
        };
      }
    }
    return this;
  }

  validatePasswordMatch(){
    if(this.data.password && this.data.confirmPassword){
       if(this.data.password !== this.data.confirmPassword){
        this.errors = {
          ...this.errors,
          confirmPassword: {
            message:
              "Password and Confirm Password fields should match",
          },
        };
       }
    }
    return this;
  }

  validateMobileNumber() {
    if (this.data.mobile){
      if(this.data.mobile.length < 10){
        this.errors = {
          ...this.errors,
          confirmPassword: {
            message:
              "Please provide valid mobile number",
          },
        };
       }
    }
      return this;
  }

  complete() {
    return {
      errors: this.errors,
      hasErrors: !!Object.keys(this.errors).length,
    };
  }
}

/* Usage */

const validation = new Validation(data, "This is a required field");
    const { hasErrors, errors } = validation
      .startValidation()
      .validateEmptyFields()
      .validateEmail()
      .validateMobileNumber()
      .validatePassword()
      .validatePasswordMatch()
      .complete();