am_running_how provides information on how the code is currently being run:

• `Node_test means that the code is being run using node as part of an expect_test
• `Node_benchmark means that the code is being run using node as part of a benchmark
• `Node means that the code is being run using node, but not as part of an expect_test or a benchmark
• `Browser_benchmark means that the code is being run in the browser as part of a benchmark
• `Browser means that the code is being run in a browser but not as part of a benchmark

am_within_disabled_fieldset traverses up the DOM to see whether an event occurred within a fieldset element with the disabled attribute. As this function requires DOM interaction, it will return false if the code is not running in the browser.

Note: because this function bubbles up from the target of the event, it's possible that the event occurs within a disabled fieldset, but the form element which performs this check is not within a disabled fieldset (or vice versa). For example, mousemove events will originate from the element under the mouse, so if the mouse is over a different disabled form, am_within_disabled_fieldset will be true, even if the component which performs this check is not.