Is it possible to use ethers.js on Polygon (Matic)?

[kuoweilai]

As the tile, can we use ethers.js functions by merely changing the provider? Or I need to use maticjs instead. I want to do a trading bot on quickswap. Sorry if this question is unorganized.
const ethers = require('ethers');

const addresses = {

WMATIC: '0x0d500B1d8E8eF31E21C99d1Db9A6444d3ADf1270',
factory: '0x5757371414417b8C6CAad45bAeF941aBc7d3Ab32',
router: '0xa5E0829CaCEd8fFDD4De3c43696c57F7D7A678ff',
recipient: '0xDe1FD04317492130A9ca13945c078bA3F5A673DC'
}

const mnemonic = 'XXXX';

const provider = new ethers.providers.WebSocketProvider('wss://rpc-mainnet.maticvigil.com/ws/v1/XXXXXX');
const wallet = ethers.Wallet.fromMnemonic(mnemonic);
const account = wallet.connect(provider);

[ricmoo]

As far as I know it should work. I haven’t used matic myself, but believe it is Ethereum compatible. Have you tried? Did it not work?

[kuoweilai]

Right now I can use websocket to access Matic, but I still can't have a success trancation. It always say cannot estimate gas. Then I tried to manually assign gasLimit but I don't know how much the gas should be.

Before:

    const tx = await router.swapExactTokensForTokens(
        amountIn,
        amountOutMin,
        [tokenIn, tokenOut],
        addresses.recipient,
        Date.now() + 1000 * 60, //1 minutes
        { gasPrice: ethers.utils.parseUnits('1', 'gwei'),
          gasLimit: await provider.getBlock('latest').gasLimit
        }
    );

Error: cannot estimate gas; transaction may fail or may require manual gas limit (error={"reason":"cannot estimate gas; transaction may fail or may require manual gas limit","code":"UNPREDICTABLE_GAS_LIMIT","error":{"code":3,"response":"{"jsonrpc":"2.0","id":6,"error":{"code":3,"message":"execution reverted: TransferHelper: TRANSFER_FROM_FAILED\

If I manually assign gas:

    const tx = await router.swapExactTokensForTokens(
        amountIn,
        amountOutMin,
        [tokenIn, tokenOut],
        addresses.recipient,
        Date.now() + 1000 * 60, //1 minutes
        {gasLimit: 1000000}
    );

But I don't really know how to give a reasonable gas in Matic. Thank you so much

[zemse]

Your swap is failing because of TRANSFER_FROM_FAILED. Check if you have enough tokenIn balance as well as allowance to the router contract.