Question about Preloading images

Discussion in 'Javascript' started by michaaal, Aug 8, 2004.

  1. michaaal

    michaaal Guest

    Is this the correct way to preload an image...?

    Var Image1 = new Image()

    ....And then when I'm ready to use the image I can do this...?

    Button1.src=Image1.src

    ....Or am I just telling Button1 to use the same source path as Image1?
     
    michaaal, Aug 8, 2004
    #1
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  2. michaaal

    Randy Webb Guest

    var is case sensitive, its lower-case v

    And you have forgotten to define the src attribute to the new Image()
    you just created.

    Image.src='url to Image';
    With the above additions, now you can.
     
    Randy Webb, Aug 8, 2004
    #2
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  3. Image1.src = ...
    ^
    Otherwise a property would be added to the constructor.
    Yes, indeed :)

    Yet it is not a very good way of preloading images, if there is some
    (preloading should be done very careful -- not only that is is not really
    required, it is unreliable [because my cache is *my* cache and client-side
    scripting may be disabled/restricted/not present] and if it works it forces
    users to download data they do not requested), it is unreliable,
    error-prone and quite hard to maintain. I have been working on another
    approach that does not show most of these problems:

    <http://pointedears.de/scripts/test/hoverMe>


    PointedEars
     
    Thomas 'PointedEars' Lahn, Aug 10, 2004
    #3
  4. michaaal

    Randy Webb Guest

    True, was a typo.
    If you want a non-script way of loading images:

    <img src="theImage.jpg" width="1" height="1" alt="">

    And its a 1 pixel dot on the page, but the image gets loaded, unless
    images are disabled and then it doesn't really matter.
     
    Randy Webb, Aug 10, 2004
    #4
  5. That may be viable for graphical browsers,
    not for other types of user agents.


    PointedEars
     
    Thomas 'PointedEars' Lahn, Aug 10, 2004
    #5
  6. michaaal

    Randy Webb Guest

    And why would you need to preload/cache images in a non-graphical user
    agent?
     
    Randy Webb, Aug 10, 2004
    #6
  7. You would not but the display of those "img" elements intended merely for
    preloading/caching could be disturbing anyway. Text browsers like lynx
    or links, e.g., can be configured to display "img" elements as a link for
    downloading the image resource as a file (to be displayed by user-defined
    graphics viewer software, for example).


    PointedEars
     
    Thomas 'PointedEars' Lahn, Aug 10, 2004
    #7
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