Blockchain Programming Code Example

The basic concept of blockchain is quite simple: a distributed database that maintains a continuously growing list of ordered records. However, it is easy to get mixed up as usually when we talk about blockchains we also talk about the problems we are trying to solve with them. This is the case in the popular blockchain-based projects such as Bitcoin and Ethereum . The term “blockchain” is usually strongly tied to concepts like transactions, smart contracts or cryptocurrencies.

This makes understanding blockchains a necessarily harder task, than it must be. Especially source-code-wisely. Here I will go through a super-simple blockchain I implemented in 200 lines of Javascript called NaiveChain.
Block structure

The first logical step is to decide the block structure. To keep things as simple as possible we include only the most necessary: index, timestamp, data, hash and previous hash.

Block hash
The block needs to be hashed to keep the integrity of the data. A SHA-256 is taken over the content of the block. It should be noted that this hash has nothing to do with “mining”, since there is no Proof Of Work problem to solve.