Swapping tokens on EVM-compatible blockchains: Mainnet, Polygon, testnets Goerli, Rinkeby. You can read blog post on this tutorial with detailed explanation.

To run this example:

1. npm install to install dependencies.

2. Customize package.json. Basically, you need to change 5 parameters of run task from scripts section

   1. --chain-id is chain ID of Ethereum chain you work with.
   2. --amount-in amount of input token you want to swap. Change according to your balance – there is no check
   3. --token-in-address smart contract address of input token
   4. --token-out-address smart contract address of output token
   5. --wallet-address your actual wallet address – replace [YOUR_WALLET_ADDRESS].

   In scripts sections you can see sample configurations for few networks (start-matic, start-rinkeby, start-goerli). In scripts-comments sections you'll find descriptions of each configuration.

3. Create .env file and put up there the following code according to network you gonna use:

   API_URL = "API_URL from https://www.alchemy.com"
   PRIVATE_KEY = "WALLET_PRIVATE_KEY"
   

   Replace API_URL with URL from Alchemy, WALLET_PRIVATE_KEY by your wallet' private key (you can get it from Metamask).

   (Don't publish these keys anywhere in public!)

4. Run configuration for certain network, e.g. npm run start-matic for Matic (Polygon) network. Please note the tutorial is for demostration purposes and it misses lots of checks.

Happy hacking!

If you have a question or something does not work, you can ask in comment section in my blog or post an issue.