Reselect Selector example for the form control. Validating a Form which has many fields using Reselect Selectors.

selector-example-2.ts

const {
  createSelector
} = Reselect;

const form = {
  firstName: 'Rakesh',
  lastName: 'Tiwari',
  age: 12,
  height: 157
};

const getFirstName = form => form.firstName;
const getlastName = form => form.lastName;
const getAge = form => form.age;
const getHeight = form => form.height;

const isNotEmptyString = (s) => s !== '';
const isValidNumber = (n) => n > 0;

const isFirstNameValid = createSelector(
  getFirstName, isNotEmptyString
);

const isLastNameValid = createSelector(
  getlastName, isNotEmptyString
);

const isAgeValid = createSelector(
  getAge, isValidNumber
);

const isHeightValid = createSelector(
  getHeight, isValidNumber
);

const isFormValid = createSelector(
  isFirstNameValid,
  isLastNameValid,
  isAgeValid,
  isHeightValid, (firstNameValid,
    lastNameValid,
    ageValid,
    heightValid) =>
  firstNameValid && lastNameValid && ageValid && heightValid
);


console.log('form is valid', isFormValid(form));

const form1 = Object.assign({},form, {age:0});

console.log('form is valid', isFormValid(form1));