JSFiddle - React, Tailwind, and code Playground

JavaScript

var date1 = new Date(Date.parse('Apr 10, 2014'));
var date2 = new Date(Date.parse('Apr 14, 2014'));

function containsWeekend(d1, d2)
{
    // note: I'm assuming d2 is later than d1 and that both d1 and d2 are actually dates
    // you might want to add code to check those conditions
    var interval = (d2 - d1) / (1000 * 60 * 60 * 24); // convert to days
    if (interval > 5) {
        return true;    // must contain a weekend day
    }
    var day1 = d1.getDay();
    var day2 = d2.getDay();
    return !(day1 > 0 && day2 < 6 && day2 > day1);
}

console.log(containsWeekend(date1,date2));