What is JavaScript FileReader?

The FileReader object lets web applications asynchronously read the contents of files (or raw data buffers) stored on the user’s computer, using File or Blob objects to specify the file or data to read. It cannot be used to read a file by pathname from the user’s file system. …

What does FileReader onload return?

The FileReader. onload property contains an event handler executed when the FileReader. load_event event is fired, when content read with readAsArrayBuffer, readAsBinaryString, readAsDataURL or readAsText is available.

What does readAsText return?

readAsText() The readAsText() method is used to read the contents of the specified Blob or File . When the read operation is complete, the readyState is changed to DONE , the loadend event is triggered, and the result property contains the contents of the file as a text string. Note: The Blob.

Is FileReader deprecated?

This node can be used to read data from an ASCII file or URL location. It can be configured to read various formats.

How do I read a .JS file?

Open Notepad or TextEdit, open the template folder, then drag the . js file into Notepad or TextEdit and drop it. Open Notepad or TextEdit, select “file” then “open”, browse to the template folder, select “all file types” and open the . js file that way.

What is FileReader result?

The FileReader result property returns the file’s contents. This property is only valid after the read operation is complete, and the format of the data depends on which of the methods was used to initiate the read operation.

Can a FileReader object be constructed that is not connected to any file?

Can a FileReader object be constructed that is not connected to any file? A. No—the constructor must specify a file.

Can JavaScript open a local file?

JavaScript cannot typically access local files in new browsers, but the XMLHttpRequest object can be used to read files. So it is actually Ajax (and not Javascript) which is reading the file.

Why BufferedReader is faster than FileReader?

Whereas, BufferedReader creates a buffer, and reads large amount of data using the given FileReader and loads it into a input buffer in the memory. Each time you want to read the file data, you can read it from the buffer( you don’t have to directly access the disk drive every time) and hence is faster than FileReader.

Why blob is used?

BLOB stands for Binary Large Object. It is defined as the chunk of binary data being stored as a single entity in a database system. BLOBs are used primarily to hold multimedia objects like images, videos, and sound, though they can also be used to store programs.

Is Blob a base64?

The reason is that BLOBs are treated in the same manner as strings because they have already been encoded by using base64 encoding before storage into a dictionary file. BLOBs stored in Spreadsheet Data Model files MUST be encoded by using base64 encoding prior to any other compression and storage.