How can I force clients to refresh JavaScript files?

Question

We are currently working in a private beta and so are still in the process of making fairly rapid changes, although obviously as usage is starting to ramp up, we will be slo

Answer 1

FRONT-END OPTION

I made this code specifically for those who can't change any settings on the backend. In this case the best way to prevent a very long cache is with:

new Date().getTime()

However, for most programmers the cache can be a few minutes or hours so the simple code above ends up forcing all users to download "the each page browsed". To specify how long this item will remain without reloading I made this code and left several examples below:

// cache-expires-after.js v1
function cacheExpiresAfter(delay = 1, prefix = '', suffix = '') { // seconds
    let now = new Date().getTime().toString();
    now = now.substring(now.length - 11, 10); // remove decades and milliseconds
    now = parseInt(now / delay).toString();
    return prefix + now + suffix;
};

// examples (of the delay argument):
// the value changes every 1 second
var cache = cacheExpiresAfter(1);
// see the sync
setInterval(function(){
    console.log(cacheExpiresAfter(1), new Date().getSeconds() + 's');
}, 1000);

// the value changes every 1 minute
var cache = cacheExpiresAfter(60);
// see the sync
setInterval(function(){
    console.log(cacheExpiresAfter(60), new Date().getMinutes() + 'm:' + new Date().getSeconds() + 's');
}, 1000);

// the value changes every 5 minutes
var cache = cacheExpiresAfter(60 * 5); // OR 300

// the value changes every 1 hour
var cache = cacheExpiresAfter(60 * 60); // OR 3600

// the value changes every 3 hours
var cache = cacheExpiresAfter(60 * 60 * 3); // OR 10800

// the value changes every 1 day
var cache = cacheExpiresAfter(60 * 60 * 24); // OR 86400

// usage example:
let head = (document.head || document.getElementsByTagName('head')[0]);
let script = document.createElement('script');
script.setAttribute('src', '//unpkg.com/sweetalert@2.1.2/dist/sweetalert.min.js' + cacheExpiresAfter(60 * 5, '?'));
head.append(script);

// this works?
let waitSwal = setInterval(function() {
    if (window.swal) {
        clearInterval(waitSwal);
        swal('Script successfully injected', script.outerHTML);
    };
}, 100);