jQuery - 确保用户连续两次在文本输入中不提交相同的值

I'm creating a magic 8 ball app where the the user enters a question in an input box. They press the submit button and the answer replaces the default html text in a heading. If the same question is asked twice in a row I want to display an alert message instead of giving a new answer. I'm new to jQuery and I can't quite figure out how to store the last value entered. I would really appreciate some input. Thank you in advance.I'm creating a magic 8 ball app where the the u