chartbeat_mab.js requests the testing “strategy” for the page the visitor is on. The strategy contains the specs of the tests that are currently active — where the tests are (which article links), what the variant headlines are, and what the current play percentages are for each variant. chartbeat_mab.js will request the strategy via asynchronous
XMLHttpRequest as soon as it loads. The strategy itself is not user cacheable, because the play percentages for each variant in each test are frequently changing as we receive data and converge on a winner for each test.