Just clone the project and run index.html. This app is accessible here.

HTML5 finally provides a standard way to interact with local files, via the File API

FileReader includes four options for reading a file, asynchronously:

• FileReader.readAsBinaryString(Blob|File) - The result property will contain the file/blob's data as a binary string. Every byte is represented by an integer in the range [0..255].
• FileReader.readAsText(Blob|File, opt_encoding) - The result property will contain the file/blob's data as a text string. By default the string is decoded as 'UTF-8'. Use the optional encoding parameter can specify a different format.
• FileReader.readAsDataURL(Blob|File) - The result property will contain the file/blob's data encoded as a data URL.
• FileReader.readAsArrayBuffer(Blob|File) - The result property will contain the file/blob's data as an ArrayBuffer object.

For our example, we want to read a CSV file, so we can read it as text. And perform data processing after in processData(csv) function.

You can read this post for more details.