['exportServlet'].submit();
(1): Indicates that all forms of the current page are obtained
(2) [0]: Indicates the first form of the current page to obtain
(3) ['exportServlet']: The form that indicates the name="exportServlet" of the current page is obtained.
(4) submit() represents the submission function
(1): Indicates that all forms of the current page are obtained
(2) [0]: Indicates the first form of the current page to obtain
(3) ['exportServlet']: The form that indicates the name="exportServlet" of the current page is obtained.
(4) submit() represents the submission function