Javascript Polyfills A polyfill is a piece of code (usually JavaScript on the Web) used to provide modern functionality on older browsers that do not natively support it. Table of Contents Array Methods Promise Methods Functions Others Array Methods map forEach filter reduce reduceRight compact concat fill find flat flatMap includes join reverse split Promise Methods Promise.all() Promise.AllSettled() Promise.any() Promise.race() Functions apply call bind Others debounce throttle memoize flatten object