topics property

The topics that must be present in the event to be included in this filter. The topics must be represented as a hexadecimal value prefixed with "0x". The encoding must have an even number of digits.

Topics are order-dependent. A transaction with a log with topics [A, B] will be matched by the following topic filters:

• [], which matches anything
• [A], which matches "A" in the first position and anything after
• [null, B], which matches logs that have anything in their first position, B in their second position and anything after
• [A, B], which matches A in first position, B in second position (and anything after)
• [[A, B], [A, B]]: Matches (A or B) in first position AND (A or B) in second position (and anything after).

The events sent by solidity contracts are encoded like this: The first topic is the hash of the event signature (except for anonymous events). All further topics are the encoded values of the indexed parameters of the event. See https://solidity.readthedocs.io/en/develop/contracts.html#events for a detailed description.