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.
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.
Go through the setup instructions for JavaScript to install the necessary dependencies:
http://exercism.io/languages/javascript/installation
The provided test suite uses Jasmine. You can install it by opening a terminal window and running the following command:
npm install -g jasmine
Run the test suite from the exercise directory with:
jasmine leap.spec.js
In many test suites all but the first test have been marked "pending".
Once you get a test passing, activate the next one by changing xit
to it
.
JavaRanch Cattle Drive, exercise 3 http://www.javaranch.com/leap.jsp
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
var Year = require('./leap');
describe('Leap year', function () {
it('is not very common', function () {
var year = new Year(2015);
expect(year.isLeap()).toBe(false);
});
xit('is introduced every 4 years to adjust about a day', function () {
var year = new Year(2016);
expect(year.isLeap()).toBe(true);
});
xit('is skipped every 100 years to remove an extra day', function () {
var year = new Year(1900);
expect(year.isLeap()).toBe(false);
});
xit('is reintroduced every 400 years to adjust another day', function () {
var year = new Year(2000);
expect(year.isLeap()).toBe(true);
});
// Feel free to enable the following tests to check some more examples
xdescribe('Additional example of a leap year that', function () {
it('is not a leap year', function () {
var year = new Year(1978);
expect(year.isLeap()).toBe(false);
});
it('is a common leap year', function () {
var year = new Year(1992);
expect(year.isLeap()).toBe(true);
});
it('is skipped every 100 years', function () {
var year = new Year(2100);
expect(year.isLeap()).toBe(false);
});
it('is reintroduced every 400 years', function () {
var year = new Year(2400);
expect(year.isLeap()).toBe(true);
});
});
});
var Year = function (input) {
this.input = input;
};
Year.prototype.isLeap = function () {
if (this.input % 400 == 0) {
return true;
} else if (this.input % 4 == 0 && this.input % 100 != 0) {
return true;
} else {
return false;
}
};
module.exports = Year;
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