Set focus on input using javascript or css on text input that is hidden until user selects an option

I am editing an existing form with inputs that are hidden until the user clicks on an option, and then text input will appear. I need to get that specific text input to have active focus once that happens. I would love to do this with CSS because I am not great with javascript, but here is a portion of that code:

if ($(“#frmSubmittedValue”).val() == ”) {
return false;
}

if ($(“#frmSubmittedValue”).val() == ‘Individual’)
$(“#personSubmittedByValue”).val(”);

if ($(“#frmProjectSub”).val() == 0) {
return false;
}

Any help is greatly appreciated!