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POHow to avoid spaghetti code in Javascript
 

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  1. POHow to avoid spaghetti code in Javascript
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    <p>I'm finding myself writing a lot of spaghetti in Javascript when I have to deal with asynchronous applications (specially when dealing with OpenSocial code where all the data has to be obtained through JS). The usual pattern is something like:</p> <ol> <li>User logs into the application for the first time, get his data.</li> <li>Do A on his data (e.g. get his friends by sending a request to the server).</li> <li>Do B on this data (e.g. send his friends to the server for some processing).</li> <li>Do C on his data (e.g. check that the server response is valid so we can do something else).</li> </ol> <p>Note that this sequential execution path (1 => 2 => 3 => 4) doesn't fit well the async. nature of Ajax so the user ends up waiting for a long time and the code turns into a mess since every step depends on the previous ones. </p> <p>An example with code:</p> <pre><code>gadgets.util.registerOnLoadHandler(setupUser()) ... function setupUser() { var req = [get data and setup request] req.send(some_url, some_data, function(response) { getFriendsFor(response.user) }); } function getFriendsFor(user) { var friends = [get friends from user] var req = [setup request] req.send(some_other_url, some_other_data, function(response { validateFriendsResponse(response.friends) }); } function validateFriendsResponse(friends) { if (friends.valid()) ... loadCanvas(); } </code></pre> <p>You can see that each function depends on the previous one, and what's worse, it has to be called in a specific order to be useful. It gets worse when you have to add stuff like showing/hiding loading screens and other gimmicks while the user waits.</p> <p>How would you go about fixing this?</p>
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    1. USFederico Builes
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    1. COCook it until it's al dente
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    2. COYour main worry seems to be that the user ends up waiting for a long time for all this to complete. Why not provide some feedback to the user after each requests returns so that they know something is happening. It could be as simple as a 3 stage progress bar, or messages telling the user what is happening. (You could even throw in a "reticulating splines" message for meme apeal.)
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      1. USSam Hasler
    3. COSam: I'm showing loading screens right now with a cute robot flapping his arms, but the code worries me too because I know I'll have some problems reading it in a couple of months.
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