使用JavaScript替换方法保留大小写/大小写

I'm continuing work on a search term suggestion tool using Jquery UI. I am now working on displaying the results with the search term pattern in bold. I have implemented this functionality through patching the Autocomplete's _renderItem method. The problem I have now is that the replaced characters have the same case as those typed by the user in the input (e.g. if the user typed an "A" and the returned result was "America", the replaced text would be I'm continuing work on a search term suggestion