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FileAPI Feedback

From: Garrett Smith <dhtmlkitchen@gmail.com>
Date: Sat, 8 Aug 2009 09:53:51 -0700
Message-ID: <c9e12660908080953x1368e8bdn3073f24dfac5463@mail.gmail.com>
To: WebApps WG <public-webapps@w3.org>
Cc: arun@mozilla.com
In glancing at some of the methods in FileAPI, I noticed some coding
errors. It seems you've made an assignment in an "if" statement and
assigned the result to window.status. I've annotated these with
comment "(GS)".

First, an overview explanation:
http://dev.w3.org/2006/webapi/FileUpload/publish/FileAPI.xhtml#dfn-getAsDataURL
|... If the call is successful, implementations MUST
| call the callback function with a string argument
| that is a valid data URL [RFC2397], and with a SUCCESS
| error code on the FileError object...

What is a SUCCESS error code? It sounds like SUCCESS is a "status"
code that would not be an error. I also understood from your prior
post that the errorHandler parameter was gone, yet I still see that in
the example code below.

I do not know why the callback takes two parameters instead of one.
The "status code" and a "getData" method could be designed as
properties of one object.


Here is your simple code review:-

| // Sample code in JavaScript
| // Obtain fileList from <input type="file"> using DOM
|
| var file = fileList.files.item(0);
| if (file)
| {
|  // ... Make asynchronous call
|
| file.getAsDataURL(handleURL);
|
| }
|
| // ...
|// (GS) What is the second parameter "error"?
| function handleURL(fileAsDataURL, error)
| {
|
| if(fileAsDataURL)
| {
|
|   // xhr.send(fileAsDataURI);
|   // Could also construct img src=fileAsDataURL
|
| }
| else
| {
| // (GS) best to keep this on local Variable object,
| // not assigning to window.status.
|   status = error.errorCode;
| // (GS) Do not perform assignment expression in "if"
| // statements.
|   if(status = error.NOT_READABLE_ERROR)
|   {
|    dump("File Not Readable");
|    // Use another asynchronous getter
|   }
| }
|}

Regards,

Garrett
Received on Saturday, 8 August 2009 16:54:32 GMT

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