Context

• node version: v4.3.0 and v4.4.4
• joi version: 8.1.0 and 9.0.0-0
• environment (node, browser): node
• used with (hapi, standalone, ...): standalone
• any other relevant information: none

What are you trying to achieve or the steps to reproduce ?

Call the validate function on the schema directly, without specifying a callback, but supplying an options object.

const Joi = require('joi');
const schema = Joi.any();
// Works
Joi.validate('test', { presence: 'optional' });
// Works
schema.validate('test');
// Throws
schema.validate('test', { presence: 'optional' });

Which result you had ?

I get the following error message:

joi/lib/any.js:666
return callback(errors, result.value);
^
TypeError: callback is not a function
at internals.Any.applyFunctionToChildren.internals.Any.validate (/tmp/testapp/node_modules/joi/lib/any.js:666:16)

What did you expect ?

The validate function should work the same way in both cases (Joi.validate and schema.validate).