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 slowing down this process. That being said, one issue we are running into is that after we push out an update with new JavaScript files, the client browsers still use the cached version of the file and they do not see the update. Obviously, on a support call, we can simply inform them to do a ctrlF5 refresh to ensure that they get the up-to-date files from the server, but it would be preferable to handle this before that time.
我们目前的想法是简单地将版本号附加到JavaScript文件的名称上，然后当进行更改时，增加脚本上的版本并更新所有引用。这肯定可以完成工作，但是在每个版本上更新引用可能会很麻烦。
我确信我们不是第一个处理这个问题的人，我想我应该把它扔给社区。当你更新你的代码时，你如何确保客户端更新他们的缓存?如果您正在使用上面描述的方法，那么您使用的是简化更改的过程吗?
前端的选择
我专门为那些不能更改后端任何设置的人编写了此代码。在这种情况下，防止超长缓存的最佳方法是:
new Date().getTime()
然而，对于大多数程序员来说，缓存可能需要几分钟或几个小时，所以上面的简单代码最终会迫使所有用户下载“所浏览的每个页面”。为了指定这个项目在不重新加载的情况下将保持多长时间，我编写了以下代码，并在下面留下了几个示例:
// 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);
jQuery函数getScript也可以用来确保每次页面加载时确实加载了js文件。
我是这样做的:
$(document).ready(function(){
$.getScript("../data/playlist.js", function(data, textStatus, jqxhr){
startProgram();
});
});
请登录http://api.jquery.com/jQuery.getScript/查看该功能
默认情况下，$. getscript()将缓存设置设置为false。这将向请求URL附加一个带有时间戳的查询参数，以确保浏览器在每次请求脚本时都会下载脚本。
