110 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
		
		
			
		
	
	
			110 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
|   | --- | ||
|  | id: 5966c21cf732a95f1b67dd28 | ||
|  | title: Date manipulation | ||
|  | challengeType: 5 | ||
|  | forumTopicId: 302244 | ||
|  | dashedName: date-manipulation | ||
|  | --- | ||
|  | 
 | ||
|  | # --description--
 | ||
|  | 
 | ||
|  | 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: `"March 6 2009 7:30pm EST"` | ||
|  | 
 | ||
|  | Example output: `"March 7 2009 7:30am EST"` | ||
|  | 
 | ||
|  | # --hints--
 | ||
|  | 
 | ||
|  | `add12Hours` should be a function. | ||
|  | 
 | ||
|  | ```js | ||
|  | assert(typeof add12Hours === 'function'); | ||
|  | ``` | ||
|  | 
 | ||
|  | `add12Hours(dateString)` should return a string. | ||
|  | 
 | ||
|  | ```js | ||
|  | assert(typeof add12Hours('January 17 2017 11:43am EST') === 'string'); | ||
|  | ``` | ||
|  | 
 | ||
|  | `add12Hours("January 17 2017 11:43am EST")` should return `"January 17 2017 11:43pm EST"` | ||
|  | 
 | ||
|  | ```js | ||
|  | assert( | ||
|  |   add12Hours('January 17 2017 11:43am EST') === 'January 17 2017 11:43pm EST' | ||
|  | ); | ||
|  | ``` | ||
|  | 
 | ||
|  | Should handle day change. `add12Hours("March 6 2009 7:30pm EST")` should return `"March 7 2009 7:30am EST"` | ||
|  | 
 | ||
|  | ```js | ||
|  | assert(add12Hours('March 6 2009 7:30pm EST') === 'March 7 2009 7:30am EST'); | ||
|  | ``` | ||
|  | 
 | ||
|  | Should handle month change in a leap years. `add12Hours("February 29 2004 9:15pm EST")` should return `"March 1 2004 9:15am EST"` | ||
|  | 
 | ||
|  | ```js | ||
|  | assert(add12Hours('February 29 2004 9:15pm EST') === 'March 1 2004 9:15am EST'); | ||
|  | ``` | ||
|  | 
 | ||
|  | Should handle month change in a common years. `add12Hours("February 28 1999 3:15pm EST")` should return `"March 1 1999 3:15am EST"` | ||
|  | 
 | ||
|  | ```js | ||
|  | assert(add12Hours('February 28 1999 3:15pm EST') === 'March 1 1999 3:15am EST'); | ||
|  | ``` | ||
|  | 
 | ||
|  | Should handle year change. `add12Hours("December 31 2020 1:45pm EST")` should return `"January 1 2021 1:45am EST"` | ||
|  | 
 | ||
|  | ```js | ||
|  | assert( | ||
|  |   add12Hours('December 31 2020 1:45pm EST') === 'January 1 2021 1:45am EST' | ||
|  | ); | ||
|  | ``` | ||
|  | 
 | ||
|  | # --seed--
 | ||
|  | 
 | ||
|  | ## --seed-contents--
 | ||
|  | 
 | ||
|  | ```js | ||
|  | function add12Hours(dateString) { | ||
|  | 
 | ||
|  |   return true; | ||
|  | } | ||
|  | ``` | ||
|  | 
 | ||
|  | # --solutions--
 | ||
|  | 
 | ||
|  | ```js | ||
|  | function add12Hours(dateString) { | ||
|  |   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`; | ||
|  | } | ||
|  | ``` |