计算后24小时输出正确的格式

Question

I'm currently using this function to calculate 2 fields and the results are good but sometimes missing a zero. sample

10:20 + 10:30 current output 0.10

10:20 + 10:30 I want the output to be 00.10

$(function () {
 function calculate() {
         time1 = $("#start").val().split(':'),
         time2 = $("#end").val().split(':');
         hours1 = parseInt(time1[0], 10), 
         hours2 = parseInt(time2[0], 10),
         mins1 = parseInt(time1[1], 10),
         mins2 = parseInt(time2[1], 10);
         hours = hours2 - hours1,
         mins = 0;
     if(hours < 0) hours = 24 + hours;
     if(mins2 >= mins1) {
         mins = mins2 - mins1;
     } else {
         mins = (mins2 + 60) - mins1;
     }

     // the result
     $("#hours").val(hours + ':' + mins);         
 }

});

also when there is an invalid character I keep getting a nan message is possible to change this to 00 instead?

Answer 1

Instead of dealing with the strings and each value independently, you can use the javascript Date object to calculate the difference...

function calculate() {

    // Get time values and convert them to javascript Date objects.
    var time1 = new Date('01/01/2017 ' + $('#start').val());
    var time2 = new Date('01/01/2017 ' + $('#end').val());
    // Get the time difference in minutes. If is negative, add 24 hours.
    var hourDiff = (time2 - time1) / 60000;
    hourDiff = (hourDiff < 0) ? hourDiff+1440 : hourDiff;
    // Calculate hours and minutes.
    var hours = Math.floor(hourDiff/60);
    var minutes = Math.floor(hourDiff%60);
    // Set the result adding '0' to the left if needed        
    $("#hours").val((hours<10 ? '0'+hours : hours) + ':' + (minutes<10 ? '0'+minutes : minutes));
}

Or even better, you can make the function independent of the DOM elements, so you can reuse it...

function calculate(startTime,endTime) {

    // Get time values and convert them to javascript Date objects.
    var time1 = new Date('01/01/2017 ' + startTime);
    var time2 = new Date('01/01/2017 ' + endTime);
    // Get the time difference in minutes. If is negative, add 24 hours.
    var hourDiff = (time2 - time1) / 60000;
    hourDiff = (hourDiff < 0) ? hourDiff+1440 : hourDiff;
    // Calculate hours and minutes.
    var hours = Math.floor(hourDiff/60);
    var minutes = Math.floor(hourDiff%60);
    // Return the response, adding '0' to the left of each field if needed.       
    return (hours<10 ? '0'+hours : hours) + ':' + (minutes<10 ? '0'+minutes : minutes);
}

// Now you can use the function.
$("#hours").val(calculate($('#start').val(),$('#end').val()));