> These days browsers may expose how many cores your device's CPU has to websites. This information could be determined prior to the introduction of navigator.

> These days browsers may expose how many cores your device's CPU has to websites. This information could be determined prior to the introduction of navigator.hardwareConcurrency. I published a timing attack polyfill that derives this information and initially proposed the navigator.hardwareConcurrency API as a replacement for this timing attack polyfill. In addition to the fundamental utility of this API, browser vendors also saw implementing this as a way to save battery life by making it no longer necessary for websites to benchmark user devices to determine this value.