javascript file2base46, return an uploaded file as base64 encoded

file2base64.js

/**
 * File2Base64
 * 
 * @param   string      file        the path of the files
 * @param   string      mim_type    the type of the file e.g: 'image/png'
 * @param   callable    callback    the callback that handle the base64encoded string
 * 
 * @author  Mohammed Al Ashaal
 * @version 1.0.0
 */
function file2base64(file, mime_type, callback)
{
    reader          =   new FileReader();
    reader.onload   =   function(e)
    {
        data = e.target.result;
        callback('data:'+mime_type+';base64,'+ btoa(data));
    };
    reader.readAsBinaryString(file);
}