isResolvableEx()
Microsoft IPv6 extension. True if the host resolves to any IPv4 or IPv6 address.
isResolvableEx(host) → booleanOnly in engines with the “Ex” extensions.
Example
if (isResolvableEx(host)) { /* ... */ }
Engine notes
| Engine | Behaviour | Source |
|---|---|---|
| pacparser | Tests the dnsResolveEx result against null, but dnsResolveEx returns "" on failure, so it is always true (read in the code, not yet probed). | code, verified 2026-10-04 |
| chromium | Tests the dnsResolveEx result against the empty string. | code, verified 2026-10-04 |
Availability
| Function | chromium | chromium | firefox | pacparser | pacparser | pacparser | reference |
|---|---|---|---|---|---|---|---|
isResolvableEx | yes | yes | no | yes | yes | yes | no |