Search in array (set) in javascript

Recently solved the problem when it was necessary to determine whether a certain (string) value falls into the set of valid values.
In JavaScript 1.6, there is an Array object's indexOf method for searching in an array, but this method is not supported in Internet Explorer. For IE, this method is implemented by looping through the array.
But since the order of the elements was not important and every millisecond was counted, I compared the performance of looping through the array with other search options (without iteration).

And the search options without busting the following:

1. Gluing an array into a string and searching in a string
   

   if (myarray.join().search( " " ) != -1) { ... }

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   When using this method, it is necessary to take into account the problem of the uniqueness of the occurrence of a search string in a string glued from an array. For this you can, for example, use gluing symbols that are not a priori found in the string:
   

   if (("#" + myarray.join("#,#") + "#").search( "# #" ) != -1) { ... }

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2. Using an object instead of an array, "array values" are hash keys
   

   if ( " " in myarray) { ... }

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To evaluate the performance of each of the three search methods, I created a test page on which 100,000 lines of the “StringN” type are created, where N is the line number, and then the string “6000000” is searched for.
It turned out that the in operator works almost instantly (runtime is always 0), even in IE6!

Test results (Celeron 2.4)

Browser	in	String.search	Array.indexOf
IE6	zero	94	2859
IE7	zero	125	390
FF2	zero	2016	31
FF3	zero	71	3
O9	zero	281	47
Safari3	zero	188	31

Search time in ms.