Using web3 and RLP to pre-calculate an address that a contract will have after deployment. Based on address and nonce.

pre_calculate_contract_address.js

/*
 * ==========
 * TypeScript
 * ==========
 */

const nonce = 6;
// Forcing type `any`, as web3 sha3 otherwise complains that it only accepts strings.
// `RLP.encode()` returns a `Buffer`.
// However, converting the buffer to a string first yields the wrong result. The buffer has to
// be passed directly into the sha3 function.
const encoded: any = RLP.encode(
  [
    account,
    nonce,
  ],
);
const nonceHash: string = this.web3.utils.sha3(encoded);
// Remove leading `0x` and first 24 characters (12 bytes) of the hex
// string leaving us with the remaining 40 characters (20 bytes) that
// make up the address.
const expectedAddress = this.web3.utils.toChecksumAddress(`0x${nonceHash.substring(26)}`);


/*
 * ==========
 * JavaScript
 * ==========
 */

// Calculate expected stake address based on key and nonce.
// Create new account so that we know the nonce is zero.
let account = await web3.eth.personal.newAccount('');
web3.eth.personal.unlockAccount(account, '');
let nonce = 0x00;

// Give new account value so it can deploy the contract.
await web3.eth.sendTransaction(
    {
        from: accounts[0],
        to: account,
        value: 120000000,
    },
);

// Calculate the address based on deploying account address and nonce.
let nonceHash = web3.utils.sha3(
    RLP.encode(
        [
            account,
            nonce,
        ],
    ),
);
// Remove leading `0x` and first 24 characters (12 bytes) of the hex
// string leaving us with the remaining 40 characters (20 bytes) that
// make up the address.
let contractAddress = nonceHash.substr(26);
// Add the leading `0x` again.
contractAddress = '0x' + contractAddress;
// Make checksum address (correct capitalization).
web3.utils.toChecksumAddress(stakeAddress);

// Deploy new contract. Make sure the newly created account deploys
// it so that the correct contract address results from the deployment.
let contract = await ContractName.new(
    args,
    {from: account},
);

// Both addresses are equal.
console.log(contract.address);
console.log(contractAddress);

it is incorrect you must use 'import { arrToBufArr, bufArrToArr } from 'ethereumjs-util'' becuz sha3 only acepts Buffers !