JSIO URLs

Posted on by

The clever bit about JSIO is the placeholder URLs – i.e. the “jsio.gif#…” that goes in your image src attributes and background-image CSS properties. Everything after the “#” is the filename of the image that should be displayed. It doesn’t have to be the filename at all, it could just be a single letter or number or symbol or whatever. It doesn’t matter to JSIO. To JSIO, everything after the “#” is just a key into the resources object that holds data uri encoded images. As long as the key is unique (which it will be if you use filenames, since no two files in the same directory can have the same name), JSIO is happy.

Using filenames as keys into our resources object is beneficial to humans. Much more beneficial than coordinates in a sprite, simply because (hopefully) the filenames are meaningful; they describe the image. In comparison to sprites, the JSIO resources object also makes maintaining your image data much easier as it is trivial to add or remove images without having to move other images around within the sprite (and consequently all coordinates referencing your moved image).

Another benefit of using filenames as keys into the JSIO resources object is for fallback. If JSIO detects your browser is IE7 or lower, it’ll strip out “jsio.gif#” leaving just your image key as the image src, which is hopefully a valid URL to the original image. Also, if JSIO detects you’re running IE8 and the image data is larger than 32KB it’ll do the same thing*.

* …but not yet in v1.0.0 alpha

Since the image key is after the “#” (it is the URL “fragment”), your browser won’t send multiple requests for the 1*1px jsio.gif file – it’ll just send one request, cache the response, and use it again. By the way, the jsio.gif image is just a transparent 1*1px gif (for maximum efficiency), but it could be an “spinner” image or something, which is shown temporarily whilst the JSIO resources file is downloaded.

—

This post is about JSIO – JSIO is a tiny library that allows you to make fewer requests to your server by packaging all your site image data in a JavaScript file in data uri format. The official site for JSIO can be found here: jsio.freestyle-developments.co.uk. You can read more about why I started this project here.

7,489 thoughts on “JSIO URLs”

  3. Hello there This is kind of off topic but I need some help from an established blog. Is it very difficult to set up your own blog? Im not very techincal but I can figure things out pretty quick. Im thinking about creating my own but Im not sure where to begin. Do you have any ideas or suggestions? Many thanks https://share.google/5KoimEtGFLFTnDINi

  38. Admiring the persistence you put into your site and detailed information you present. Its great to come across a blog every once in a while that isnt the same old rehashed material. Wonderful read Ive bookmarked your site and Im including your RSS feeds to my Google account. https://share.google/jLuPVBLGINkorhVYY

  43. Unquestionably imagine that that you stated. Your favourite reason seemed
    to be on the internet the simplest factor to remember of.
    I say to you, I definitely get irked whilst
    people think about worries that they just do not know about.
    You managed to hit the nail upon the highest and
    also defined out the entire thing without having side-effects , other people can take a signal.

    Will probably be again to get more. Thank you

  44. Покупка шаблона «Аспро Максимум» — быстрый способ запустить мощный интернет-магазин на 1С-Битрикс без долгой разработки. Переходите по запросу цена Аспро Макс. Вы получите готовую структуру, адаптивный дизайн, продуманный каталог и встроенные инструменты для продаж и SEO. Решение легко настраивается под задачи бизнеса и помогает выйти на рынок в кратчайшие сроки.

  45. согласование перепланировки квартиры в москве согласование перепланировки квартиры в москве .

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>