如何将yyyy-mm-dd日期转为带序数词的dd month yyyy格式？

Alright, let's build that stringifyTheDate function you need. Here's a clear breakdown of the required logic, plus a working implementation that handles all edge cases like 11th, 12th, 13th (which don't follow the standard ordinal rules):

Core Logic Steps #

• Parse the input date: Split the yyyy-mm-dd string into separate year, month, and day components. Remember, the input month is 1-based (e.g., 04 = April), so we'll need to adjust it for zero-indexed arrays later.
• Map month numbers to full names: Create an array of month names (January to December) so we can convert the numeric month (like 4) to its full text equivalent ("April").
• Generate ordinal suffixes: Calculate the correct suffix for the day (st, nd, rd, th). Special cases apply for days 11-13—they all use "th" regardless of the last digit.
• Construct the final string: Combine the day + suffix, full month name, and year into the desired format (e.g., "21st April, 2018").

Working Implementation (JavaScript) #

function stringifyTheDate(actual_date) {
  // Split the input into year, month, day (convert to numbers)
  const [year, month, day] = actual_date.split('-').map(Number);
  
  // Full month names (zero-indexed, so month 1 = index 0)
  const monthNames = [
    'January', 'February', 'March', 'April', 'May', 'June',
    'July', 'August', 'September', 'October', 'November', 'December'
  ];
  const monthName = monthNames[month - 1]; // Adjust for 1-based input month
  
  // Helper function to get ordinal suffix
  const getOrdinalSuffix = (day) => {
    if (day >= 11 && day <= 13) return 'th';
    switch (day % 10) {
      case 1: return 'st';
      case 2: return 'nd';
      case 3: return 'rd';
      default: return 'th';
    }
  };
  
  // Combine all parts into the final formatted string
  return `${day}${getOrdinalSuffix(day)} ${monthName}, ${year}`;
}

// Test with your example
const actual_date = '2018-04-21';
const date = stringifyTheDate(actual_date);
console.log(date); // Output: "21st April, 2018"

Notes on Edge Cases #

• This handles all tricky ordinal scenarios: 11th, 12th, 13th, 21st, 22nd, 23rd, 31st, etc.
• The function assumes your input is a valid yyyy-mm-dd string. If you need to handle invalid inputs, you can add validation checks (e.g., ensuring the month is between 1-12, day is valid for the month/year).

内容的提问来源于stack exchange，提问作者Mukesh Aryal