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# lujanfernaud's solution

## to Leap in the JavaScript Track

Published at Aug 15 2018 · 0 comments
Instructions
Test suite
Solution

#### Note:

This exercise has changed since this solution was written.

Given a year, report if it is a leap year.

The tricky thing here is that a leap year in the Gregorian calendar occurs:

``````on every year that is evenly divisible by 4
except every year that is evenly divisible by 100
unless the year is also evenly divisible by 400
``````

For example, 1997 is not a leap year, but 1996 is. 1900 is not a leap year, but 2000 is.

If your language provides a method in the standard library that does this look-up, pretend it doesn't exist and implement it yourself.

## Notes

Though our exercise adopts some very simple rules, there is more to learn!

For a delightful, four minute explanation of the whole leap year phenomenon, go watch this youtube video.

## Setup

Go through the setup instructions for ECMAScript to install the necessary dependencies:

http://exercism.io/languages/ecmascript

## Requirements

Install assignment dependencies:

``````\$ npm install
``````

## Making the test suite pass

Execute the tests with:

``````\$ npm test
``````

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by changing `xtest` to `test`.

## Source

JavaRanch Cattle Drive, exercise 3 http://www.javaranch.com/leap.jsp

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### leap.spec.js

``````import Year from './leap';

describe('A leap year', () => {
test('year not divisible by 4: common year', () => {
const year = new Year(2015);
expect(year.isLeap()).toBeFalsy();
});

xtest('year divisible by 4, not divisible by 100: leap year', () => {
const year = new Year(2016);
expect(year.isLeap()).toBeTruthy();
});

xtest('year divisible by 100, not divisible by 400: common year', () => {
const year = new Year(2100);
expect(year.isLeap()).toBeFalsy();
});

xtest('year divisible by 400: leap year', () => {
const year = new Year(2000);
expect(year.isLeap()).toBeTruthy();
});
});``````
``````class Year {
constructor(year) {
this.year = year;
}

isLeap() {
if (this.year % 4 === 0 && this.year % 100 !== 0) { return true; }

return this.year % 400 === 0;
}
}

export default Year;``````