Returns a bool indicating whether this object's path is absolute.
On Windows, a path is absolute if it starts with \\ or a drive letter between a and z (upper or lower case) followed by :\ or :/. On non-Windows, a path is absolute if it starts with /.
Source
bool get isAbsolute {
if (Platform.isWindows) {
return path.startsWith(_absoluteWindowsPathPattern);
} else {
return path.startsWith('/');
}
}