path.isAbsolute(path)

//Posix examples:
path.isAbsolute('/foo/bar') // true
path.isAbsolute('/baz/..') // true
path.isAbsolute('qux/') // false
path.isAbsolute('.') // false
//Windows examples:
path.isAbsolute('//server') // true
path.isAbsolute('C:/foo/..') // true
path.isAbsolute('bar//baz') // false
path.isAbsolute('.') // false

// windows version
  exports.isAbsolute = function(path) {
    var result = splitDeviceRe.exec(path),
        device = result[1] || '',
        isUnc = device && device.charAt(1) !== ':';
    // UNC paths are always absolute
    return !!result[2] || isUnc;
  };