would you please explain me the conditional part ?

   ...
/* here str is split at the space, resulting in an array, which is assigned back to str variable.  So str ends up being converted onto an array or words. The for-construct iterates over this array. */
   str = str.split(" ");
   ...
     // key gets initialized to one of the words in the str array.
     key = str[i];

     // initially, result is initialized to an empty object => result={}.
     // In javascript, you can dereference an property using either of the following syntax:
     // result.ask
     // or
     // result['ask']
     // since I don't know the words ahead of time, I can't use the first form.  
     // So I used the second form, but used a variable instead of the literal word.
     // Initially, there is no such thing as result['ask'], so the else clause will execute
     // result['ask'] = 1; (but remember, the variable key contains 'ask' on the first iteration -- when i == 0)
     // The same logic applies for each word the first time they are encountered. 
     // Thus, when the second 'a' is encountered , result['a'] does exist -- it was initialized to 1 the first time around
     // So this time typeof(result['a']) is NOT "undefined" -- it was defined the first time it encountered 'a'.
     if( "undefined" != typeof(result[key]) )
        result[key]++;
     else
        result[key]=1;

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@ hielo
thank you . i m still lost with the explanation . thanks anyways

much much better !!! i am reading and repeating the order . Thank you again.