<img> onload vs complete

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manu3d@gmail.com - 31 Jul 2006 16:08 GMT

Hi everybody,

I'm using the event "onload" to trigger a function when an
image has been preloaded. But it seems to me that the
function is triggered right at the beginning of the transfer
from remote to local rather than at the end of it.

Can anybody confirm this?

Thank you.

Manu

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Yanick - 31 Jul 2006 17:24 GMT

http://www.w3schools.com/jsref/jsref_onload.asp

has your information. Don't you love W3Schools ? :)

If you have troubles running your code, I suggest one of the following

1) verify if you have errors using alert debug windows and such (i.e. :
alert( var_to_test );)

2) use setTimeout() to delay the execution of the code

3) employ this to wrap your JS inside the <img> event attribute :

<img src="blah.gif" onload="//<![CDATA[
/** some js code here **/
//]]>" />

Read about it here : http://en.wikipedia.org/wiki/CDATA

But frankly, good coding rarely make it to solution 2) as it should run
correctly in solution 1).

Hope this helps.

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Richard Cornford - 31 Jul 2006 18:32 GMT

> http://www.w3schools.com/jsref/jsref_onload.asp
>
> has your information. Don't you love W3Schools ? :)

Yes; partial information and falsehoods put across as if it was
definitive.

<snip>

> 3) employ this to wrap your JS inside the <img> event attribute :
>
> <img src="blah.gif" onload="//<![CDATA[
> /** some js code here **/
> //]]>" />

When you have absolutely no idea why you are recommending something it
would probably be better not to mention it at all. This is a mystical
incantation, and can achieve nothing.

> Read about it here : http://en.wikipedia.org/wiki/CDATA

<snip>

A page that never suggests the above nonsense, or even implies anything
about it.

Richard.

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Joe D Williams - 31 Jul 2006 20:46 GMT

> Richard wrote:
> > Yanick wrote:
[quoted text clipped - 15 lines]
> would probably be better not to mention it at all. This is a mystical
> incantation, and can achieve nothing.

Using CDATA is not a 'mystical incantation' when used as required by
the XML application to set aside parsing the CDATA content.

>> Read about it here : http://en.wikipedia.org/wiki/CDATA
> <snip>
>
> A page that never suggests the above nonsense, or even implies anything
> about it.

Well. it does mention
'The term indicates that a certain portion of the document
is general character data, rather than non-character data or character
data with a more specific, limited structure.'
In some XML applications, the idea of 'general character data' is exploited
to hide an inline script from the operations that deal with figuring out the
rest of the XML user code.

For example:

...
<Script DEF='OpenVault'>
...
<![CDATA[ ecmascript:
function combinationEntered (value) {
unlocked = value;
}
function openVault(value) {
if (unlocked) vaultUnlocked = value;
}
]]>
</Script>

http://www.web3d.org/x3d/specifications/ISO-IEC-19776-X3DEncodings-XML-ClassicVR
ML/Part01/examples.html#ScriptingExample

This is the special case of a Script node in a specific XML application that
also generally applies to inline script handling in XHTML tools.

> Richard.

Fortunately, in that application, like others, there is a way to get rid of
the
CDATA or equivalent wrapper. Instead, just include the url to the script
location.

Thanks and Best Regards,
Joe

Reply to this Message

Richard Cornford - 31 Jul 2006 22:12 GMT

>> Richard Cornford wrote:
>>> Yanick wrote:

<snip>

>>> 3) employ this to wrap your JS inside the <img> event attribute :
>>>
[quoted text clipped - 8 lines]
> Using CDATA is not a 'mystical incantation' when used as required
> by the XML application to set aside parsing the CDATA content.

<snip>

Which is irrelevant to placing CDATA style mark-up inside the value of
an intrinsic event attribute in either HTML or XHTML. In neither case
could that CDATA style mark-up ever be interpreted as declaring CDATA,
and the result only avoids being a syntax error by being the text of
comments. Given that, the above most certainly is a mystical
incantation; it does precisely nothing in reality and is only being
'used' (rather than being weeded out as an obvious error) because it
does precisely nothing in reality.

Richard.

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Webmaster Forum / HTML, CSS, Scripts / JavaScript / July 2006

<img> onload vs complete