How can I serialize an input File object to JSON?

Question

I want to convert an HTML input file to a JSON string like this:

var jsonString = JSON.stringify(file);
console.log( file );
console.log( jsonString );
         


        

Answer 1

You have to read the file content using the FileReader API. The File object does not contain the file content (it is just a pointer toward the file, which allows you to read it later).

You can check out this HTML5Rocks article to find out more about the usage of this API.

var file = getAFile( );

var success = function ( content ) {
  console.log( JSON.stringify( content ) ); }

var fileReader = new FileReader( );
fileReader.onload = function ( evt ) { success( evt.target.result ) };
fileReader.readAsText( file );