根据月份名称获取 ISO 日期字符串

Question

I have to create two ISO date strings in an Array based on the long month name.

Input: 'August'
Output: ['2020-08-01T00:00:00', '2020-08-31T00:00:00']

I am thinking about a switch case to check for each month but I am not sure how to create the ISO string with this information. I could match August with 08 and replace a pre-defined ISO string and replace it based on the input but this doesn't sound very clever.

Answer 1

You can get the month names from toLocaleString for the locale you are in or hardcode an array.

Then calculate the first of this month and the 0th of NEXT month

I had to normalise the time to 15:00 to handle timezones.

 const yyyy = new Date().getFullYear(); const months = Array.from(Array(12).keys()) .map(month => new Date(yyyy, month, 5, 15, 0, 0, 0) .toLocaleString('default', { month: 'long'}) ); const zeroTime = str => `${str.split("T")[0]}T00:00:00`; const getDates = month => { const monthNum = months.indexOf(month); const start = new Date(yyyy, monthNum, 1, 15, 0, 0, 0), end = new Date(yyyy, monthNum+1, 0, 15, 0, 0, 0) return [zeroTime(start.toISOString()), zeroTime(end.toISOString())]; }; console.log(getDates("August"))

Answer 2

There are many ways to go about this, the only real issue is how to generate the list of month names. The following uses mplungian's approach of generating them in the browser default language, though I'm not sure that's a good idea.

The other part of the problem is to generate timestamps for the start and end of the month. That's pretty simple given a year and month number. You can use UTC values and toISOString , then trim the trailing Z to get local timestamps.

The following should be efficient as it only generates one date and array to get the month names, then one more of each on each call of getMonthDates . It also uses for loops instead of creating arrays and using array methods for iteration.

It also provides separate functions for getting the month number from the name and dates from month number and year. They use ECMAScript month number (0 = Jan, etc.) but could easily be converted to use calendar month number (1 = Jan, etc.).

 // Given year and ECMAScript month number, return an array of ISO 8601 // formatted local timestamps for first and last days of the month let getMonthDates = (monthNum = 0, year = new Date().getFullYear()) => { let date = new Date(Date.UTC(year, monthNum)); let start = date.toISOString().substring(0, 19); date.setUTCMonth(monthNum + 1, 0); return [start, date.toISOString().substring(0, 19)]; } // Given a month name, return it's ECMAScript month number // Uses host default language for month name let getMonthDatesFromName = (() => { let date = new Date(); let monthNames = (() => { date.setMonth(0, 1); for (var arr=[], i=0; i<12; i++) { arr.push(date.toLocaleString('default',{month:'long'})); date.setMonth(i+1) } return arr; })(); return (monthName, year) => { let monthNum = monthNames.indexOf(monthName); // If month name not found, return undefined return monthNum < 0? void 0 : getMonthDates(monthNum, year); } })(); /** getMonthDatesFromName examples */ // Undefined if month name not valid console.log('foo: ' + getMonthDatesFromName('foo')); // Current month name let monthName = new Date().toLocaleString('default',{month: 'long'}); console.log(monthName + ': ' + getMonthDatesFromName(monthName).toString()); // February, 2024 console.log('February, 2024: ' + getMonthDatesFromName('February', 2024).toString()); /** getMonthDates examples */ // January of current year by default console.log('Default: ' + getMonthDates().toString()); // Month of current year by default, eg for April console.log('April: ' + getMonthDates(3).toString()); // Month and year - February 2024 console.log('1, 2024: ' + getMonthDates(1, 2024).toString());