Lesson 9: hardhat vs localhost about chainId 31337

[GaneshDonikena]

Hi everyone!! @PatrickAlphaC ,
why can't we use "localhost" instead of "hardhat' in hardhat-config.js file as shown below to match with helper-hardhat-config.js file:

networks: {
        hardhat: {
            chainId: 31337,
        },
        rinkeby: {
            chainId: 4,
            url: RINKEBY_RPC_URL,
            accounts: [PRIVATE_KEY],
        },
    },

const networkConfig = {
  
    31337: {
        name: "localhost",
        subscriptionId: "588",
        gasLane: "0xd89b2bf150e3b9e13446986e571fb9cab24b13cea0a43ea20a6049a85cc807cc", // 30 gwei
        keepersUpdateInterval: "30",
        raffleEntranceFee: "100000000000000000", // 0.1 ETH
        callbackGasLimit: "500000", // 500,000 gas
    },

[zeroxvee]

You can do that. But localhost is reserved for our own node that we run by yarn hardhat node. So don't forget to explicitly choose localhost yarn hardhat deploy --network localhost

[alymurtazamemon]

@GaneshDonikena As @vbazhutin said you also need to run localhost in other terminal

[krakxn]

We can, the following is my config:

        hardhat: {
            // // If you want to do some forking, uncomment this
            // forking: {
            //   url: MAINNET_RPC_URL
            // }
            chainId: 31337,
        },
        localhost: {
            chainId: 31337,
        },

localhost is for when we run up our own node; whereas hardhat is for Hardhat's comprehension - even if you do not specify and make it explicit, Hardhat will do it automatically