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.

11,442 thoughts on “JSIO URLs”

  8. Arkadaşlar merhaba Siteler sürekli değişiyor erişim engelleniyor Aylardır araştırıyorum Hiç takılmadan çalışıyor — 1xbet türkiye lider bahis Canlı destek gece gündüz aktif Neyse kendiniz kontrol edin — birxbet giriş birxbet giriş Tek adres 1xbet güncel giriş Bahis yapan herkese gönder

  18. I am really enjoying the theme/design of your site.
    Do you ever run into any browser compatibility issues? A number of my blog visitors have complained about my website not working correctly in Explorer
    but looks great in Firefox. Do you have any ideas to help fix this issue?

    Here is my webpage … מיכלאמברםשחר

  20. whoah this blog is magnificent i really like studying your posts.
    Stay up the great work! You know, lots of persons are looking round for this
    information, you could aid them greatly.

  36. Arkadaşlar merhaba Bazı apk dosyaları çalışmıyor Virüslü dosyalara denk geldim Sonunda doğru apk dosyasını buldum — 1xbet apk yükle kolay Bonuslar ve promolar her gün var Neyse kendiniz indirin — 1xbet download android 1xbet download android Tek adres 1xbet apk Bahis yapan herkese gönder

  40. I think the admin of this site is genuinely working hard in favor of his website, because here every information is quality
    based material.

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>