Go through the setup instructions for JavaScript to install the necessary dependencies:

http://exercism.io/languages/javascript

Execute the tests with:

jasmine <exercise-name>.spec.js

Replace <exercise-name> with the name of the current exercise. E.g., to test the Hello World exercise:

jasmine hello-world.spec.js

In many test suites all but the first test have been skipped.

Once you get a test passing, you can unskip the next one by changing xit to it.