JSFiddle - React, Tailwind, and code Playground

JavaScript

var x = "22:10";
var y = "23:15";

function createDate(v) {
    var date = new Date(),
        va = v.split(':');
    
    date.setHours(va[0]);
    date.setMinutes(va[1]);
    
    return date;
}

function getDiff(x, y) {
    var date1 = createDate(x),
        date2 = createDate(y);
    
    var result = new Date();
    result.setTime(date2.getTime() - date1.getTime());
    
    var hours = result.getUTCHours().toString(),
        minutes = result.getUTCMinutes().toString();
    
    if (hours.length == 1) {
        hours = '0' + hours;
    }

    if (minutes.length == 1) {
        minutes = '0' + minutes;
    }
    
    return hours + ':' + minutes;
}

var diff = getDiff(x, y);

alert(diff);