轻日期到字符串格式

Posted 2021-02-23

I don't really know how other people do this kind of thing, but this was my take.

//Test It
formatDate(new Date().getTime(), 's/ss : m/mm : h/hh : D/DD : d/dd/ddd/ddd : M/MM/MMM/MMMM : yy/yyy : t/tt');
 
//Declare It
function formatDate(dateInMs, formatString)
{
	if(typeof dateInMs == 'number' && typeof formatString == 'string')
	{
		var dateObj = new Date(parseInt(dateInMs));
		var dateString = '';
		var dayArray = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
		var monthArray = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
 
		for(var i = 0; i < formatString.length; i++)
		{
 
			switch(formatString[i])
			{
				case 's': //'ss' for leading zero
					if(formatString[i+1] == 's') {
						dateString += (dateObj.getSeconds() >= 10 ? '' : '0') + dateObj.getSeconds();
						i++;
					}
					else {
						dateString += dateObj.getSeconds();
					}
					break;
				case 'm': //'mm' for leading zero
					if(formatString[i + 1] == 'm') {
						dateString += (dateObj.getMinutes() >= 10 ? '' : '0') + dateObj.getMinutes();
						i++;
					}
					else {
						dateString += dateObj.getMinutes();
					}
					break;
				case 'h': //'hh' for leading zero
					var military = dateObj.getHours();
					var standard = military > 12 ? military-12 : military;
					if(formatString[i + 1] == 'h') {
						standard = (standard >= 10 ? '' : '0') + standard;
						i++;
					}
					dateString += standard;
					break;
				case 'D': // This is for day of month //'DD' for leading zero
					if(formatString[i + 1] == 'D') {
						dateString += (dateObj.getDate() >= 10 ? '' : '0') + dateObj.getDate();
						i++;
					}
					else {
						dateString += dateObj.getDate();
					}
					break;
				case 'd': //This is for day of week //'dd' for leading zero, 'ddd' for abbreviated day name, 'dddd' for full day name
					if(formatString[i + 1] == 'd' && formatString[i + 2] == 'd' && formatString[i + 3] == 'd') {
						dateString += dayArray[dateObj.getDay()];
						i = i + 3;
					}
					else if(formatString[i + 1] == 'd' && formatString[i + 2] == 'd') {
						dateString += dayArray[dateObj.getDay()].substr(0, 3);
						i = i + 2;
					}
					else if(formatString[i + 1] == 'd') {
						dateString += '0' + dateObj.getDay();
						i++;
					}
					else {
						dateString += dateObj.getDay();
					}
					break;
				case 'M': //'MM' for leading zero, 'MMM' for abbreviated month name, 'MMMM' for full month name
					if(formatString[i + 1] == 'M' && formatString[i + 2] == 'M' && formatString[i + 3] == 'M') {
						dateString += monthArray[dateObj.getMonth()];
						i = i + 3;
					}
					else if(formatString[i + 1] == 'M' && formatString[i + 2] == 'M') {
						dateString += monthArray[dateObj.getMonth()].substr(0, 3);
						i = i + 2;
					}
					else if(formatString[i + 1] == 'M') {
						dateString += (dateObj.getMonth() >= 10 ? '' : '0') + dateObj.getMonth();
						i++;
					}
					else {
						dateString += dateObj.getMonth();
					}
					break;
				case 'y': //'yy' for two-digit number, 'yyyy' for four-digit number
					if(formatString[i + 1] == 'y' && formatString[i + 2] == 'y' && formatString[i + 3] == 'y') {
						dateString += dateObj.getFullYear();
						i = i + 3;
					}
					else if(formatString[i + 1] == 'y') {
						dateString += String(dateObj.getFullYear()).substr(2, 2);
						i++;
					}
					else {
						dateString += formatString[i]
					}
					break;
				case 't': //'t' first character of am/pm, 'tt' for both characters of am/pm
					var military = dateObj.getHours();
					var ampm = military > 12 ? 'pm' : 'am';
 
					if(formatString[i + 1] == 't') {
						dateString += ampm;
						i++;
					}
					else {
						dateString += ampm.substr(0, 1);
					}
					break;
				default:
					dateString += formatString[i]
			}
		}
 
		return dateString;
	}
	else
	{
		console.error('Invalid date or formatString provided to formatDate(). Try sending time in milliseconds and a format string.');
		return '';
	}
}