javascript - 如何计算JavaScript中两个“HHmm”之间的小时数？

是否可以计算两个“ HHmm”字符串之间的分钟或小时数。

JavaScript示例：

var now = 2050,
    next = 0850,
    minutesUntilNext = *now until then code*,
    hoursUntilNext = *minutes to hours code*;

我无权访问实际的Date对象，这就是为什么这有点难的原因。
但是我正在使用moment.js，因此如果您有关于如何在此中使用它的建议
情况，那将是完美的。

最佳答案

通过一些基本的除法和减法，这是非常简单的：

// http://stackoverflow.com/a/10075654/560648
function padDigits(number, digits) {
    return Array(Math.max(digits - String(number).length + 1, 0)).join(0) + number;
}

/**
 * Given two times in HHMM format, returns the timespan between them
 * in HH:MM format.
 *
 * %next is assumed to come later than %now, even if its absolute value
 * is lower (so, the next day).
 */
function compareTimes(now, next) {

   // Perform hours validation before we potentially add 24 hours (see below)
   if (now >= 2400 || next >= 2400)
      throw "Hours out of bounds";

   // If next is "earlier" than now, it's supposed to be tomorrow;
   // adding 24 hours handles that immediately
   if (next < now) next += 2400;

   // Split inputs into hours and minutes components
   now  = [parseInt(now  / 100, 10), now  % 100];
   next = [parseInt(next / 100, 10), next % 100];

   // Finally, validate the minutes
   if (now[1] >= 60 || next[1] >= 60)
      throw "Minutes out of bounds";

   // Perform the comparisons
   var minutesUntilNext = next[1] - now[1];
   var hoursUntilNext   = next[0] - now[0];

   // And return the result
   return padDigits(hoursUntilNext, 2) + ':' + padDigits(minutesUntilNext, 2);
}

console.log(doThisThing(2050, 0850));  // 12:00
console.log(doThisThing(2300, 0145));  // 02:45
//console.log(doThisThing(2500, 0000));  // error
//console.log(doThisThing(2460, 0000));  // error