Espruino/tests/test_FS_API_1_Read.js

// read and write both take a number of bytes and position as the second and third arguments.
// 0 is a valid position, so -1 is used to indicate "don't care" or "current position".
var fd = new File('./tests/FS_API_Test.txt','r');
var buffer="";
fd.read(buffer,6,22);
fd.close();
result = (buffer == "FS API");