yyyy-mm-dd Formats a Date as yyyy-MM-dd. Usage $ npm install yyyy-mm-dd(...)$ node> let yyyymmdd = require('yyyy-mm-dd')undefined> yyyymmdd()'2015-04-29'> yyyymmdd.withTime()'2015-04-29 16:51:09'> yyyymmdd(new Date(1999, 0, 1))'1999-01-01'