Here is the time:

01:02:25,369

I want to subtract 10 seconds from it, so the return value should be:

01:02:15,369

I know I have to write a function to do so, but things get difficult when seconds are <10 so you have to subtract minutes and hours as well.

CodePudding user response：

You could just convert it to milliseconds and then add or subtract however much you want. And then make a render function to convert it back into a string if you need it.

function getTotalMS(timeString) {
    const [hms, ms] = timeString.split(',');
    const [h, m, s] = hms.split(':');

    return parseInt(ms) * 1  
           parseInt(s) * 1000  
           parseInt(m) * 60 * 1000  
           parseInt(h) * 60 * 60 * 1000;
}

function renderTime(ms) {
    const h = Math.floor(ms / (60 * 60 * 1000)); ms -= h * 60 * 60 * 1000;
    const m = Math.floor(ms / (60 * 1000)); ms -= m * 60 * 1000;
    const s = Math.floor(ms / (1000)); ms -= s * 1000;

    return `${h<10?'0':''}${h}:${m<10?'0':''}${m}:${s<10?'0':''}${s},${ms}`;
}


// subtracting 10 seconds
let totalTime = getTotalMS('01:02:25,369');
totalTime -= 10 * 1000;
console.log(renderTime(totalTime));

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

probably could be optimized, but here's a starting point

CodePudding user response：

Turn it into a Date, then subtract 10000 (don't reinvent the wheel)