css - Using JavaScript to invalidate the browser's cache - Stack Overflow

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I'm doing a project in Django and using djangos-css () and Sass (/). The Sass files are served in development using django-css. I want to write a JavaScript routine that will every one second retrieve the CSS assets. The purpose of this is so that the designer can edit the Sass files, hit save, and see the result in the browser immediately without switching applications and hitting refresh.

Basically I need a way for JavaScript to force the browser to re-download certain files without doing a page refresh. Is this possible?

I'm doing a project in Django and using djangos-css (http://github./dziegler/django-css) and Sass (http://sass-lang./). The Sass files are served in development using django-css. I want to write a JavaScript routine that will every one second retrieve the CSS assets. The purpose of this is so that the designer can edit the Sass files, hit save, and see the result in the browser immediately without switching applications and hitting refresh.

Basically I need a way for JavaScript to force the browser to re-download certain files without doing a page refresh. Is this possible?

• javascript
• css
• caching
• sass

Share Improve this question Follow edited Jan 31, 2010 at 0:30 hekevintran asked Jan 30, 2010 at 20:43 hekevintranhekevintran 23.7k3434 gold badges116116 silver badges182182 bronze badges

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2 Answers 2

Sorted by: Reset to default 3

The simplest way is usually to add a unique parameter onto the url, I often just use a timestamp

var timestamp = (new Date()).getTime();
url += '?time=' + timestamp;

Just be careful if your requests already have parameters then you need to add &time=' + timstamp instead.

The browser can't cache the request because each request looks unique.

Not all caches will cache content with a query string.

Steve Souders remends, “…avoiding a querystring for cacheable resources”. He found that in this case 5-20% of requests will not be cached. Query strings in particular do not work at all with some CDNs for cache invalidation.

The better way is to generate a MD5 with the javascript file name for each release e.g.

{path to script file}/filename-{md5 hash}.js

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