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Re: XMLHttpRequest and Google Chrome

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On 13/04/15 18:29, Tim Streater wrote:
> In article <mggqp5$cu6$1@dont-email.me>, Robbie Brown <rob@example.com>
> wrote:
>
>> On 13/04/15 16:46, Christoph M. Becker wrote:
>>> Robbie Brown wrote:
>>>
>> <snip>
>>
>>>> Can anyone put me out of my misery?
>>>
>>> The onload property of the window element is supposed to hold the
>>> reference to a Function object (or null).  This function object is
>>> automatically called (with a single argument, namely the respective
>>> Event object[1]) after the documented has been loaded.
>>>
>>> In your case you're assigning the return value of getCart() to the
>>> property.  The return value is undefined, and will be cast to null, so
>>> no function will be called when the document has been loaded.
>>>
>>> Instead getCart is called right before the assignment, which causes the
>>> XHR to be triggered immediately.  The rest is timing dependend.
>>
>> I'm starting to think it's a timing issue, maybe I've been lucky to
>> have things working so far. I still don't understand this whole
>> getCart versus getCart() thing, maybe it's something fundamental that
>> I'm missing.
>
> You need to assign a function to the onload property. In fact you
> already do this sort of thing here:
>
> function getReadyStateHandler(req, responseXmlHandler) {
>    return function () { ... }
>
> and here:
>
> req.onreadystatechange = getReadyStateHandler(req, updateCart);
>
> where your getReadyStateHandler function returns a reference to a
> function (don't argue, yes it does, it says "return function ...").
>
> In exactly the same way, this code:
>
>>> <script type="text/javascript">
>>>     window.onload=getCart();
>>> </script>
>
> ought to assign a function to the onload handler. The function you want
> to assign is getCart, hence you need to say:
>
>   window.onload = getCart;
>
> This will cause getCart to be run when the onload is complete and not
> before. With what you had, getCart is run as soon as:
>
>   window.onload=getCart();
>
> is encountered, which will likely be before the onload is complete,
> meaning that <div id="cartsnapshot"> may or may not be known to the
> browser at that point. So whether it works or not is down to timing.
>
> So - notice the difference between:
>
>   window.onload = getCart;
>
> and:
>
>   <body onload="getCart();">
>
> The first requires a function reference. In the second, you put some
> javascript to be executed. So you could put:
>
>   <body onload="alert('Boo!');">
>
> and to get the same effect with window.onload needs:
>
>   window.onload = function () { alert('Boo!'); };

OK, I did a test.

In <head> I have

<script type="text/javascript">>
	window.onload = getCart();
</script>

In getCart() I put an alert as the first line

(incidentally getCart() is in a file that is referenced thusly in <head>
<script type="text/javascript" src="/javascript/cart.js"></script>
before the call obviously)

alert("hello");

when I load any page in Firefox (and occasionally in Chrome) I get 
"hello" *before* the page is displayed

if I change <head>

<script type="text/javascript">
	window.onload = getCart;
</script>

The function doesn't get called, I get no "hello"
This is the same in all my browsers. I have no idea why as you and 
others say that getCart should work, it simply doesn't. I'm not making 
it up, it doesn't execute, I'm not mistaken, so, obviously something is 
still missing.

So it's back to the drawing board and javascript console.

Thank you all for all your help but the problem still exists.



-- 
Not floundering ... just fishing

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Thread

XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-12 19:36 +0100
  Re: XMLHttpRequest and Google Chrome JJ <jj4public@vfemail.net> - 2015-04-13 12:33 +0700
    Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 07:41 +0100
  Re: XMLHttpRequest and Google Chrome Martin Honnen <mahotrash@yahoo.de> - 2015-04-13 11:30 +0200
    Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 11:50 +0100
      Re: XMLHttpRequest and Google Chrome Tim Streater <timstreater@greenbee.net> - 2015-04-13 13:17 +0100
        Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 13:34 +0100
          Re: XMLHttpRequest and Google Chrome Tim Streater <timstreater@greenbee.net> - 2015-04-13 14:26 +0100
          Re: XMLHttpRequest and Google Chrome Martin Honnen <mahotrash@yahoo.de> - 2015-04-13 16:15 +0200
            Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 16:03 +0100
              Re: XMLHttpRequest and Google Chrome Martin Honnen <mahotrash@yahoo.de> - 2015-04-13 19:26 +0200
                Re: XMLHttpRequest and Google Chrome "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-04-13 20:23 +0200
          Re: XMLHttpRequest and Google Chrome Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-13 15:50 +0100
            Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 16:10 +0100
              Re: XMLHttpRequest and Google Chrome "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-04-13 17:46 +0200
                Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 17:28 +0100
                Re: XMLHttpRequest and Google Chrome "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-04-13 19:14 +0200
                Re: XMLHttpRequest and Google Chrome Tim Streater <timstreater@greenbee.net> - 2015-04-13 18:29 +0100
                Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 18:59 +0100
                Re: XMLHttpRequest and Google Chrome "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-04-13 20:29 +0200
                Re: XMLHttpRequest and Google Chrome Tim Streater <timstreater@greenbee.net> - 2015-04-13 19:34 +0100
                Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 20:11 +0100
                Re: XMLHttpRequest and Google Chrome "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-04-13 20:44 +0200
                Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 20:21 +0100
                Re: XMLHttpRequest and Google Chrome Denis McMahon <denismfmcmahon@gmail.com> - 2015-04-14 12:43 +0000
                Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-14 14:50 +0100
                Re: XMLHttpRequest and Google Chrome Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-04-14 22:51 +0200
                Re: XMLHttpRequest and Google Chrome Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-04-13 22:28 +0200
  Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-13 19:23 +0100
    Re: XMLHttpRequest and Google Chrome Tim Streater <timstreater@greenbee.net> - 2015-04-13 19:38 +0100
  Re: XMLHttpRequest and Google Chrome "Leonardo Azpurua" <leonardo@exmvps.org> - 2015-04-13 17:36 -0430
  Re: XMLHttpRequest and Google Chrome Robbie Brown <rob@example.com> - 2015-04-14 11:35 +0100
  Re: XMLHttpRequest and Google Chrome Denis McMahon <denismfmcmahon@gmail.com> - 2015-04-14 11:37 +0000

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