JQuery. unique triggers a murder

In the project development process, PM said that the system only needs to run in a specific browser, but there cannot be logic errors in other browsers. Therefore, during the development process, chrome browser is selected for the front-end and backend, and Firefox and IE are not carefully tested. However, yesterday PM reflected a bug, which is a browser compatibility bug. It works normally in Chrome, but no error is reported in IE, but the logic is incorrect. Remove complex business logic and streamline the Code as follows: copy the Code