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New Contributor
Posts: 3
Registered: ‎10-25-2012
My Device: PlayBook
My Carrier: No Carrier
Accepted Solution

How to read top 200 bytes of a file

I have to read top n bytes of a set of very big files in the system in my WebWorks app but I don't know how to implement it. Please help me.

 

Thanks

Retired
Posts: 6
Registered: ‎10-08-2012
My Device: developer
My Carrier: Telus

Re: How to read top 200 bytes of a file

Hi huydq5000, 

 

Using the FileReader you can use the function called readAsBinaryString(blob)

 

Suppose you had a File object named file and a FileReader object named reader.

You can use file.slice(startByte, endByte) to obtain a Blob chunk of your File object, in your case it would be something like:

 

reader.readAsBinaryString(file.slice(0, n));

 

Take a look at the "Slicing a File" section in this link:
http://www.html5rocks.com/en/tutorials/file/dndfiles/