JS——求某年某月某天是多少天

最新推荐文章于 2022-11-29 11:18:51 发布

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#javascript #求天数

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本文提供了两种不同的JavaScript实现方式来计算从年初至今的天数。第一种方法通过条件判断为每个月加上对应的天数，考虑了平年与闰年的情况；第二种方法使用switch-case结构，同样区分平年与闰年的二月天数。

var year = Number(prompt("输入年："));
		var month = Number(prompt("输入月："));
		var day = Number(prompt("输入日："));

		var flag = 0;

		if((year % 4 == 0 && year % 100 !=0) || (year % 400) == 0){
			flag = 1;
		}

		if(month == 1){
			console.log(day);
		}
		if(month == 2){
			console.log(31 + day);
		}
		if(month == 3){
			if(flag == 0){
				console.log(59 + day);
			}
			if(flag == 1){
				console.log(60 + day);
			}
		}
		if(month == 4){
			if(flag == 0){
				console.log(90 + day);
			}
			if(flag == 1){
				console.log(91 + day);
			}
		}
		if(month == 5){
			if(flag == 0){
				console.log(120 + day);
			}
			if(flag == 1){
				console.log(121 + day);
			}
		}
		if(month == 6){
			if(flag == 0){
				console.log(151 + day);
			}
			if(flag == 1){
				console.log(152 + day);
			}
		}
		if(month == 7){
			if(flag == 0){
				console.log(181 + day);
			}
			if(flag == 1){
				console.log(182 + day);
			}
		}
		if(month == 8){
			if(flag == 0){
				console.log(212 + day);
			}
			if(flag == 1){
				console.log(213 + day);
			}
		}
		if(month == 9){
			if(flag == 0){
				console.log(243 + day);
			}
			if(flag == 1){
				console.log(244 + day);
			}
		}
		if(month == 10){
			if(flag == 0){
				console.log(273 + day);
			}
			if(flag == 1){
				console.log(274 + day);
			}
		}
		if(month == 11){
			if(flag == 0){
				console.log(304 + day);
			}
			if(flag == 1){
				console.log(305 + day);
			}
		}
		if(month == 12){
			if(flag == 0){
				console.log(334 + day);
			}
			if(flag == 1){
				console.log(335 + day);
			}
		}

----------------------------------------------------------------------------------

第二种方法：

var year = Number(prompt("输入年："));
		var month = Number(prompt("输入月："));
		var day = Number(prompt("输入日："));

		var isrun = (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);

		var totaldays = 0;

		switch(month - 1){ //从case11逐级递减 很巧妙 无break，可以不断加下去
			case 11:
				totaldays += 30;
			case 10:
				totaldays += 31;
			case 9:
				totaldays += 30;
			case 8:
				totaldays += 31;
			case 7:
				totaldays += 31;
			case 6:
				totaldays += 30;
			case 5:
				totaldays += 31;
			case 4:
				totaldays += 30;
			case 3:
				totaldays += 31;
			case 2:
				isrun ? totaldays += 29 : totaldays += 28;
			case 1:
				totaldays += 31;
		}

		totaldays += day;

		console.log(totaldays);