Up to date, up to the minute, highly fashionable. Compare "à la mode". Also as adverb: in accordance with the latest fashion; very fashionably.
à la page/ˌa la ˈpɑːʒ/ /ˌa lə ˈpɑːʒ/ /ˌɑː lɑː ˈpɑːʒ/
1930s; earliest use found in The French Review. From French à la page, literally ‘on the page’ from à la + page.