jQuery Instant Upload plugin

This fairly simple instant upload plugin turns any DOM element into a button that uploads a user-chosen file to the server through the forms mechanism, in a fashion somewhat similar to sending an ajax request.

Usage

$(element).upload({
    url: '',
    name: '',
    enctype: 'multipart/form-data',
    select: function(filename, id) { },
    submit: function(id) {},
    error: function(error, id) {},
    success: function(response, id) {},
    complete: function(id) {}
});

Most options should be pretty self-explanatory, but here goes:

• url: the url to send the upload request to; if unspecified, uses the action from the parent form of the element
• name: the name attribute for the uploader; if unspecified, uses the name attribute of the element
• enctype: the enctype attribute of the form used to upload the data, most of the time this should be left unchanged
• select: user-defined function, which is called whenever the user chooses a file to upload, but before the request is actually sent; use this to validate the choice, and return false to stop the upload from starting
• submit: user-defined function, which is called just before uploading
• error: called in case an error happened during the upload, with the error detail as the first argument
• success: called if the upload succeeded, with the server response as the first argument
• complete: this function is called after the upload request is done, whether it was successful or not

All of the parameters are optional. All of the user-defined callbacks include the current uploader id as the last arg. Whenever a request is sent, the id changes, which allows one to use oen uploader to upload multiple files.