How to check if a file is already open

Question

My question is about the local file system object `File`. I am writing a function that reads the contents of a text file. The function is passed a `File` object as an argument and then reads the content before some other logic.

Before you can read a `File` object it needs to be open. The Adobe JavaScript documentation has the following warning around opening files:

NOTE: Be careful about opening a file more than once. The operating system usually permits you to do so, but if you start writing to the file using two different File objects, you can destroy your data.

So my question is... How do I tell if a File object is already open? There doesn't appear to be a property or method that simply tells me this.

Jump_Over · Accepted Answer

Hi,Suggest to use method file.tell() ==> which returns "-1" if current position cant be retrieved.If file is opened it returns number >=0 .Jarek

TᴀW · Answer

Just a thought: Perhaps you can try reading from the file first without opening it. If this fails, it's closed. If it succeeds, that would mean it's already open.

I do not know if this approach works though -- haven't tested it.

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