Jasmine is a behavior-driven development framework for testing JavaScript code. It uses a syntax that is very similar to RSpec, with describe blocks to group specs and expectations, and hooks like beforeEach, afterEach, beforeAll and afterAll. Both frameworks support expectations, stubbing, mocking, and error handling in a comparable way. The document provides examples of common testing patterns in Jasmine and compares them side-by-side to their RSpec equivalents to illustrate how Rubyists can easily transition to testing JavaScript with Jasmine.