The code evaluates to 0 or 1 which are both true.

Unfortunately, javascript is evaluating if(0) as false making the code
inside the statement never fire.

inArray returns -1 if the value is not found in the array. So I just added
>= 0 for the code to fire properly.

Author: Jao Zafra

lib/assets/javascripts/autocomplete-rails-uncompressed.js

@@ -79,7 +79,7 @@
                 options[key] = attrVal ? attrVal : value;
               }
             });
-            if(arguments[0].length == 0 && jQuery.inArray(options.showNoMatches, [true, 'true'])) {
+            if(arguments[0].length == 0 && jQuery.inArray(options.showNoMatches, [true, 'true']) >= 0) {
               arguments[0] = [];
               arguments[0][0] = { id: "", label: options.noMatchesLabel };
             }