in lib/h3core.js [879:888]
export function cellToCenterChild(h3Index, res) {
const [lower, upper] = h3IndexToSplitLong(h3Index);
const centerChild = C._malloc(SZ_H3INDEX);
try {
throwIfError(H3.cellToCenterChild(lower, upper, res, centerChild));
return validateH3Index(readH3IndexFromPointer(centerChild));
} finally {
C._free(centerChild);
}
}