javascript - Computing SHA1 hash of a file in Google Drive -

i need compute sha-256 hash of file uploaded via ajax google drive in appscript deployed web-app. in server code, computing this:

function gethash(file) {   var hashbytes = utilities.computedigest(utilities.digestalgorithm.sha_256, file.getblob().getdataasstring());   // convert raw bytes base16-encoded string   var hash = "";   for(var i=0; i<hashbytes.length; i++) {     var byte = hashbytes[i];     if(byte < 0) {       byte += 256;     }     var bytestring = byte.tostring(16);     // if byte not represented 2 chars must 0-padded     if(bytestring.length == 1) {       bytestring = '0' + bytestring;     }     hash += bytestring; return hash;   } 

however, computed hash different 1 same file e.g. executing

shasum -a 256 myfile

in bash shell. there wrong in gethash() function?

i'd need function work on file type.