JSFiddle - React, Tailwind, and code Playground

JavaScript

var convertTime = function (input, separator) {
    var pad = function(input) {return input < 10 ? "0" + input : input;};
    return [
        pad(Math.floor(input / 3600)),
        pad(Math.floor(input % 3600 / 60)),
        pad(Math.floor(input % 60)),
    ].join(typeof separator !== 'undefined' ?  separator : ':' );
}

document.body.innerHTML = '<pre>' + JSON.stringify({
    5.3515555 : convertTime(5.3515555),
    126.2344452 : convertTime(126.2344452, '-'),
    1156.1535548 : convertTime(1156.1535548, '.'),
    9178.1351559 : convertTime(9178.1351559, ':'),
    13555.3515135 : convertTime(13555.3515135, ',')
}, null, '\t') +  '</pre>';