jsc.heapSize

Returns the size of the JavaScript heap in bytes: the objects that survived the most recent garbage collection, plus the memory they own outside the heap (string contents, ArrayBuffer contents). Objects allocated since the last collection are not included, so call fullGC first for an up-to-date number.

This is the heapSize field of heapStats without the rest of the statistics. For the memory usage of the whole process, use memoryUsage.