Cordova 文件插件 FileReader.readAsText 获取错误但不调用错误回调

Question

I am using Cordova File plugin to read a JSON on local filesystem. It works perfectly except for some file where I get an error :

SyntaxError: Unexpected EOF

These files probably have wrong characters and I need to fix them but my problem is not there. My problem is that the plugin logs the error (on the javascript side) but never calls any error callback !!!

When I debug and I follow step by step, on the javascript side I get to the exec() command in FileReader.js, I then follow step by step in objectiveC and it seems perfectly fine, but when ObjectiveC returns it results back with its sendPluginResult, I get this error message in javascript console and no error callback is thrown....

Anybody ever experienced this ? Any idea to catch the error ?

Thank you very much.

Answer 1

I don't know if you solved your problem, but I had a similar issue, which was solved by changing $cordovaFile.readAsText to $cordovaFile.readAsBinaryString , with no other changes. No more EOF problems.

I've hunted the invisible characters, removed newlines and escaped everything possible. Changing the file reader to readAsBinaryString solved the problem.

Answer 2

There is a known bug in the Cordova file plugin's readAsText method , which means that files larger than 256 kB containing non-ASCII characters may fail with this error message.

readAsText() reads files in 256 kB chunks. With variable-width encodings like UTF-8 , if there's a multibyte character straddling the chunk boundary, then it will be split into two different byte sequences, each of which will be treated as a character.

When the JS environment tries to concatenate the first hunk with such a split character, it sees a byte sequence that's not allowed in a string and throws a SyntaxError.

Since there is no test data attached to this question, I can't be sure this is what happened here, but it seems likely. The symptoms line up.

The GitHub issue I linked above suggests a workaround, which is to use the readAsArrayBuffer() method and to use the browser built-in TextDecoder.decode() method to convert to the correct encoding for your file.