What does “[, something]” mean in jQuery documentation?

Answer 1

The "[, something]" in the jQuery documentation means that an argument to that function is optional.

Let's take the jQuery.ajax( url [, settings ] ) function for example (via https://api.jquery.com/jquery.ajax/). jQuery has defined that the "url" variable to this function is required. However, the "settings" argument is optional and not needed unless you want some unique settings during the call.

Therefore, both of these uses of the function would be valid:

jQuery.ajax(url)

jQuery.ajax(url, settings)