best practice for loading necessary JSON data: jquery's $(document).ready() hook? in the <HEAD> of page?

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+2 Q:

best practice for loading necessary JSON data: jquery's $(document).ready() hook? in the <HEAD> of page?

Hi everyone,

I have been reading Yahoo's Best Practices For Speeding Up Your Website, but still have a question that I could really use your help with:

The very first page of my web app needs to display a bunch of data that is dependent on the city the user is in. On the first visit, the user is prompted to pick her city and I store a cookie in the browser recording which city to start with. On her following visits to the site, the Javascript code checks the cookie and retrieves the data for that city as JSON.

Given that this data is necessary to display the fundamental part of the page, where should I load it from? Currently I am doing it from the top of Jquery's $(document).ready(), but it occurred to me that by definition that only gets executed once the entire page has loaded.

Which is the correct way to do this? (Eg, will it improve matters if I instead put some Javascript in the that checks for the cookie and loads the JSON feed for the right city? Some other solution...?)

Thank you for any insight

lara

+3 A:

Currently I am doing it from the top of Jquery's $(document).ready(), but it occurred to me that by definition that only gets executed once the entire page has loaded.

$(document).ready() will be called when the DOM is ready for manipulation, not when the entire page has loaded. The DOM will be ready as soon as the markup has been read and parsed into the DOM. This occurs before the entire page has loaded.

Putting your code to check the cookie value and retrieve city-specified data in $(document).ready() is perfectly fine.

Jon Cram 2009-12-13 21:29:50

If you really need this data to show the page correctly, how about simply inlining the data in the page itself? Save yourself an AJAX round-trip, be nice to your users in sub-Saharan Africa on the 300 baud modem.

Bruce 2009-12-13 21:31:42

Point taken, but (unfortunately!) I don't think we will be covering sub-Saharan cities any time soon. : )The way we are doing the site is to have the HTML pages be static (ie, not dynamically generated).

laramichaels 2009-12-13 21:52:11

I think the $(document).ready() is as soon as you can do it, although I'm not sure why you wouldn't just inspect the cookie values on the first request. Just check to see if they are set, and if they are, get the content for the user there are save yourself having to make any AJAX call. Maybe I'm missing something in your situation, but cookies are always sent with every request to a specific domain so AJAX/JavaScript shouldn't be necessary.

Bialecki 2009-12-15 01:50:21

ansaurus

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best practice for loading necessary JSON data: jquery's $(document).ready() hook? in the <HEAD> of page?

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