General - solidity ethereum

Useful tool

Remix has a built in debugger that helps debug contracts
        

Solidity Gotcha's

Nested dynamic arrays cannot be used with the combination of both solidity and javascript

[
    [1,2,3],
    [4,5,6],
]

Solidity stores strings as dynamic arrays, ergo, something like:

const colors = ["red", "green", "blue"]

cannot be used. Pending solution in Grider course.

        

Get provider

# ganache is a test network
const ganache = require("ganache-cli");
const Web3 = require("web3");
const web3 = new Web3(ganache.provider());
        

Get all accounts on network

web3.eth.getAccounts().then((fetchedAccounts) => {
    console.log(fetchedAccounts);
});
        

Get value from contract

const message = await inbox.methods.message().call();
        

Modify a contract's data / Send a transaction to our contract

# sends transaction from first account
await inbox.methods.setMessage("bye").send({ from: accounts[0] });
        

Function that someone can send money along with 0.4.17

function enter() public payable {
    players.push(msg.sender);
}
        

Require global variable

require(msg.value > 0.01 ether)

# should error out if the message sender doesn't send enough ether
# require is a builtin helper

        

Send ether to address

players[index].transfer(this.balance)

address.transfer is the function