When Nightwatch runs a test, it processes its commands in a list known as the command queue. This list manages the asynchronous execution of the commands defined in that test. As a queue, the command queue generally follows the rule of first in, first out (FIFO). The first command you call in a test is the first executed when the test runs. The second command is called next, followed by the next command up until the last command added, which becomes the last command executed.
Understanding the Command Queue · nightwatchjs/nightwatch Wiki