javascript replace text in multiple HTML files with other text

I would like create a javascript that automatically find and replace a text variables with another ones in multiple HTML files, for instance:

text to search (located as is in HTML files):

%%LNG_SyndicateNewProducts%% %%LNG_SyndicateNewProductsAtom%% %%LNG_SyndicateNewProductsIntro%% %%LNG_SyndicateNewProductsRSS%% %%LNG_SyndicateNews%% %%LNG_SyndicateNewsAtom%% etc. etc.

text to replace (located all in a file):

Produse noi Ultimele % Produse Noi (Atom) Ultimele produse încărcate conţin ultimele %s produse adăugate pe %. Ultimele %s Produse Noi (RSS) Noutăţi etc.

Anyone can help me?

Thanks, Coel