How to distinguish a "ether pay" transaction with a "function call" transaction

Question

So basically we can find many transaction histories within each block, like this:

https://etherscan.io/txs?block=1506816

So my question is that, since on Ethereum we can do the following four kinds of transaction, how I can figure out which transaction it is, by just looking at their transaction page on etherscan?

• account -> account
• smart contract -> smart contract (could be a function call, or simply send some ethers and trigger its call back)
• account -> smart contract
• smart contract -> account

Answer 1

Each transaction has always the two following fields:

• from account
• to account

The web3 library provides a function called web3.eth.getCode to retrieve the smart contract code at a given address. If the code returned is 0x, we can deduce that this is a individual account.

web3.eth.getCode("0x7f6eab1759ab5cae0ba484422406736a884a140d", function(err,res) {
    if(err) throw err;
    if(res == "0x") {
        console.log("Individual Account address ") 
    } else {
        console.log("Smart contract Account address")
    }
});

Examples:

https://rinkeby.etherscan.io/address/0x6dff9c7c1a821190c9f3b34a835a01dd58c90af0

>> web3.eth.getCode("0x6dff9c7c1a821190c9f3b34a835a01dd58c90af0", function(err,res) {console.log(res)});
>> 0x

https://rinkeby.etherscan.io/address/0x7f6eab1759ab5cae0ba484422406736a884a140d

>> web3.eth.getCode("0x7f6eab1759ab5cae0ba484422406736a884a140d", function(err,res) {console.log(res)});
>> 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Answer 2

You can identify if an address is a smart contract by checking if bytecode exists when you query the address:

https://web3js.readthedocs.io/en/1.0/web3-eth.html#getcode

web3.eth.getCode("0xd5677cf67b5aa051bb40496e68ad359eb97cfbf8")
.then(console.log);
> "0x600160008035811a818181146012578301005b601b6001356025565b8060005260206000f25b600060078202905091905056"

If it is a normal EOA, then the result will be 0x. At that point, you can determine both parties of a transaction, and ultimately what kind of transaction it is.

Etherscan also shows the contract information if it is present.