Arrow Functions are one of the greatest additions in ES6, whether it's regarding the this keyword or regarding the shorter syntax.

Today we will see, how using arrow functions makes our code much simpler and shorter while creating validation functions.

Suppose, you have written a function which returns true if the email is valid otherwise returns an error message as shown below:

const validateEmail = email => /^[^@ ]+@[^@ ]+\.[^@ \.]+$/.test(email);
const isValidEmail = function(value) {
    if (validateEmail(value)) {
        return true;
    } else {
        return "Please enter a valid email address";
    }
}

let isValid = isValidEmail('abc@gmail.com');
console.log(isValid); // true
isValid = isValidEmail('abc@@gmail.com');
console.log(isValid); // Please enter a valid email address

The same function can be written in just one line using ES6 arrow functions syntax as shown below:

const validateEmail = email => /^[^@ ]+@[^@ ]+\.[^@ \.]+$/.test(email);
const isValidEmail = value => validateEmail(value) || 'Please enter a valid email address.';

let isValid = isValidEmail('abc@gmail.com');
console.log(isValid); // true
isValid = isValidEmail('abc@@gmail.com');
console.log(isValid); // Please enter a valid email address

---

Suppose you have written a generic validation function that checks if the input field is empty or not as shown below:

const isNotEmpty = function(fieldName) {
  return function(fieldValue) {
    if (fieldValue.trim().length > 0) {
      return true;
    } else {
      return fieldName[0].toUpperCase() + fieldName.slice(1) + " is required.";
    }
  };
};

const fieldName = isNotEmpty('name');
let isValid = fieldName('David');
console.log(isValid); // true
isValid = fieldName('');
console.log(isValid); // Name is required

The same function can be written in just one line using ES6 arrow functions syntax as shown below:

const isNotEmpty = fieldName => fieldValue => fieldValue.trim().length > 0 || fieldName[0].toUpperCase() + fieldName.slice(1) + ' is required.';

const fieldName = isNotEmpty('name');
let isValid = fieldName('David');
console.log(isValid); // true
isValid = fieldName('');
console.log(isValid); // Name is required

These are just two examples of validation functions but as you can see, you can create all validation functions using this ES6 arrow function syntax which allows us to write code in a simpler and shorter way.

Thanks for reading!

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