Find the Pure Function

// 1

function add(a, b) {
  return a + b;
}

Find the Pure Function

// 2

const sum = 0;

function addToSum(a) {
  sum + a;
}

Find the Pure Function

// 3

const rounding = true;

function divide(a, b) {
  const result = a / b;

  if (rounding) {
    result = parseInt(result);
  }

  return result;
}

Find the Pure Function

// 4

function isTuesday() {
  const today = new Date;

  return today.getDay() === 2;
}

Find the Pure Function

// 5

function luckyNumber() {
  return parseInt(Math.random() * 10);
}

Find the Pure Function

// 6

function add(a, b) {
  const sum = a + b;

  console.log('Sum is: ', sum);

  return a + b;
}

Answers

The answer is 1.

2 is not a pure function because it makes changes to the value of external variable.

3 is not a pure function because it depends on the external state.

4 is not a pure function because it uses current time inside the function which is a global state.

5 is not a pure function because its result depends on random number. It will not generate the same result every time.

6 is not a pure function because it produces some side effect printing out the result.

Date Functions

Get which day is Today?

Date Functions

Get current year?

Date Functions

Get current month?

Date Functions

Write function which return remaining days in the year.

• // Cuurent Time

  const now = new Date();

  // Start of the year

  const start = new Date(now.getFullYear(), 0, 0);

  // Differnce

  const diff = now - start;

  // One Day

  const oneDay = 1000 * 60 * 60 * 24;

  // Today's Day

  const day = Math.floor(diff / oneDay);

  // Remaining Day's in the year

  const daysLeft = 365 - day;

  console.log('Day of year: ' + daysLeft);