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---
title: Date manipulation
id: 5966c21cf732a95f1b67dd28
challengeType: 5
2019-08-05 16:17:33 +00:00
forumTopicId: 302244
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---
## Description
< section id = 'description' >
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Given a date string in EST, output the given date as a string with 12 hours added to the time. Time zone should be preserved.
Example input: < code > "March 7 2009 7:30pm EST"< / code >
Example output: < code > "March 8 2009 7:30am EST"< / code >
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< / section >
## Instructions
< section id = 'instructions' >
< / section >
## Tests
< section id = 'tests' >
```yml
tests:
- text: < code > add12Hours</ code > is a function.
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testString: assert(typeof add12Hours === 'function');
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- text: < code > add12Hours(dateString)</ code > should return a string.
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testString: assert(typeof add12Hours('January 17 2017 11:43am EST') === 'string');
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- text: < code > add12Hours("January 17 2017 11:43am EST")</ code > should return < code > "January 17 2017 11:43pm EST"</ code >
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testString: assert(add12Hours('January 17 2017 11:43am EST') === 'January 17 2017 11:43pm EST');
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- text: Should handel day change. < code > add12Hours("March 7 2009 7:30pm EST")</ code > should return < code > "March 8 2009 7:30am EST"</ code >
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testString: assert(add12Hours('March 7 2009 7:30pm EST') === 'March 8 2009 7:30am EST');
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- text: Should handel month change in a leap years. < code > add12Hours("February 29 2004 9:15pm EST")</ code > should return < code > "March 1 2004 9:15am EST"</ code >
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testString: assert(add12Hours('February 29 2004 9:15pm EST') === 'March 1 2004 9:15am EST');
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- text: Should handel month change in a common years. < code > add12Hours("February 28 1999 3:15pm EST")</ code > should return < code > "March 1 1999 3:15am EST"</ code >
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testString: assert(add12Hours('February 28 1999 3:15pm EST') === 'March 1 1999 3:15am EST');
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- text: Should handel year change. < code > add12Hours("December 31 2020 1:45pm EST")</ code > should return < code > "January 1 2021 1:45am EST"</ code >
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testString: assert(add12Hours('December 31 2020 1:45pm EST') === 'January 1 2021 1:45am EST');
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```
< / section >
## Challenge Seed
< section id = 'challengeSeed' >
< div id = 'js-seed' >
```js
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function add12Hours(dateString) {
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// Good luck!
return true;
}
```
< / div >
< / section >
## Solution
< section id = 'solution' >
```js
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function add12Hours(dateString) {
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const months = ['January', 'February', 'March', 'April', 'May', 'June',
'July', 'August', 'September', 'October', 'November', 'December'];
// Get the parts of the string
const parts = dateString.split(' ');
const month = months.indexOf(parts[0]);
const day = parseInt(parts[1], 10);
const year = parseInt(parts[2], 10);
const time = parts[3].split(':');
let hours = parseInt(time[0], 10);
if (time[1].slice(-2) === 'pm') {
hours += 12;
}
const minutes = parseInt(time[1].slice(0, -2), 10);
// Create a date with given parts, and updated hours
const date = new Date();
date.setFullYear(year, month, day);
date.setHours(hours + 12); // Add 12 hours
date.setMinutes(minutes);
let hoursOutput = date.getHours();
let abbreviation = 'am';
if (hoursOutput > 12) {
hoursOutput -= 12;
abbreviation = 'pm';
}
return `${months[date.getMonth()]} ${date.getDate()} ${date.getFullYear()} ${hoursOutput}:${date.getMinutes()}${abbreviation} EST` ;
}
```
< / section >