Michael Geary schrieb:
> The "{lat=xxx, lon=xxx}" must a typo? That is neither JSON nor JavaScript.
>
>
:) Right. I'm writing too much today...
> Proper JSON would look like this (the whitespace is optional):
>
> { "lat": 40.0, "lng": -120.0 }
>
>
Right.
> BTW, the quotes on the property names are required for correct JSON format,
> although they don't matter if you're just generating executable JavaScript.
>
> By adding the variable assignment, you've changed the response from JSON to
> executable JavaScript code.
>
>
OK
> However, that's not a complete solution. How do you know when your script
> has loaded? You don't get notified that a variable has been assigned into.
>
>
That's what I'm doing using the timer approach. Look into Jürgens first
answer in this thread.
> That's why JSONP uses a callback, not a variable assignment. If the server
> response is:
>
>
> mycallback({ "lat": 40.0, "lng": -120.0 })
>
>
Yes, this seems to be a better solution. I'll try that.
> Then you *know* when it's loaded, because your "mycallback" function is
> called at that time.
>
> Now you don't have to use a timer (BAD idea!). You don't have to worry about
> readystatechange. You don't have to do any of that. You simply have a
> function in your JavaScript code that *automatically* gets called at exactly
> the right moment.
>
> As I mentioned in my other message, the customary way to do this is to
> provide a callback function name in the URL, such as:
>
> http://example.com/myjsonservice?foo=bar&abc=xyz&callback=callme
>
> Then the server would generate:
>
> callme({ "lat": 40.0, "lng": -120.0 })
>
>
Yepp. This is what I've seen, but obviously not understood, in many GOOG
requests with Wireshark.(Was only interested in the HTTP "flesh", not in
the JS stuff)
> This places control of the actual function name in the client code.
>
> You don't *have* to do that; you can have a hard coded callback function
> name if you want. But the conventional JSONP approach used by many sites
> lets the client specify the callback name. Most JavaScript libraries such as
> jQuery now have built-in support for JSONP with a callback - it's really the
> way to go.
>
>
OK. Thanks Mike, this was a very interesting lesson. But what about the
"not cross-domain" claim?
> -Mike
>
>
>> From: Neil.Young
>>
>> Exactly. The "straight" JSON, delivered until now by my
>> server, didn't work the very first attempt. Reason: I was
>> missing the assignment statement, so the plain JSON object
>> "{lat=xxx, lon=xxx}" had to be delivered padded with a
>> variable assignment, e.g. "data = {lat=xxx, lon=xxx}" by the server.
>>
>> But Micheal: Why this?
>>
>> JSON is not executable JavaScript and cannot be used
>> cross-domain without a proxy.
>>
>>
>> I think, "cross-domaining" is of course possible, but it is
>> probably hard to deal with the results? The server side is
>> called in any case...
>> Or do I catch that wrong? For me XMLHttpRequest is not cross
>> domain and cannot be used w/o proxy, that's for sure.
>>
>
>
> >
>
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