Lesson 9: Passing an argument to a function raffle.enterRaffle() with no parameters

[tsuccar]

I need a clarification on usage of a function in "scripts/enter.js" script. Two questions :

1. raffle.enterRaffle() takes { value: entranceFee + 1 } as argument. if this function refers by name to the same function In Raffle.sol contract, it was not coded to take any parameters. how are we able to pass the argument above ?

2. Why does the argument have entranceFee plus 1. why is 1 added on top of the fee ?

async function enterRaffle() {
    const raffle = await ethers.getContract("Raffle")
    const entranceFee = await raffle.getEntranceFee()
    await raffle.enterRaffle({ value: entranceFee + 1 })
    console.log("Entered!")
}

enterRaffle()
    .then(() => process.exit(0))
    .catch((error) => {
        console.error(error)
        process.exit(1)
    })`

[othaime-en]

Hey @tsuccar

1. You are right, the enterRaffle function does not take any parameters, however, it is payable and has to receive some ETH before allowing anybody to enter the raffle as evidenced by the snippet below.

if (msg.value < i_entranceFee) {
            revert Raffle__NotEnoughETHEntered();
    }

As we know, we have to pay some eth when calling the enterRaffle function for us to enter the raffle and the method used in the code above it how we send eth with our transactions (Yes. Calling a function is a transaction). So in this case, {value: entranceFee + 1} isn't really a parameter, more like a value/data that we send along with our transaction. When we send like this, the eth becomes available globally inside the contract through the method msg.value and that's what was being check in the if statement I have shared above.
2. Not really sure why Patrick used + 1 in the entrance fee but the most plausible one is to make sure that whatever we send is above the entranceFee. Either way, if you fail to add 1 you will still enter the raffle.

[tsuccar]

Thank you !

[krakxn]

2. Going by sheer memory here, but does enterRaffle() have any conditional (or invokes some other function specific for such a purpose) in it? If not, it is to account for gas.