Rinkeby Uniswap swapExactETHForTokens - Fail with error 'UniswapV2Router: EXPIRED' - node.js

Question

Ideally, I need example of correct transaction format in web3 or ethers,
Where it can swap WETH for ERC20 or ERC20 for WETH using UniswapV2Router on Rinkeby,
I think, I'm having wrong transaction format, maybe it's because of gasPrice or gasLimit, but I don't understand where it happens, So I tried with the increased gasPrice(100 Gwei) and gasLimit(8,000,000) but it's still failing, I also decreased the "amountOutMin" to 1,
Transaction deadline is 20 minutes but it's failiing in a few seconds
Swap 1 Ether for UNI (WETH and ETH balances are more than 5 on sender's address)
transaction deadline: 20 minute
UNI address: 0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984
UniswapV2Router: 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
Another small question, when you swap ETH for ERC20 does it takes WETH or ETH from senders balance?
const swap = async () => {
try{
const chainId = ChainId.RINKEBY
const tokenAddress = "0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984"
const uni = await Fetcher.fetchTokenData(chainId, tokenAddress)
const weth = WETH[chainId]
const pair = await Fetcher.fetchPairData(uni, weth)
const route = new Route([pair], weth)
const trade = new Trade(route, new TokenAmount(weth, '100000000000000000'), TradeType.EXACT_INPUT)
console.log('1 WETH for', route.midPrice.toSignificant(6), ' UNI')
console.log('1 UNI for', route.midPrice.invert().toSignificant(6), ' WETH')
console.log('Trade price 1 WETH for ', trade.executionPrice.toSignificant(6), ' UNI')
const accounts = await web3.eth.getAccounts()
const account = accounts[0]
const slippageTolerance = new Percent('20', '100')
const path = [weth.address, uni.address ]
const to = account
// function toHex(currencyAmount) {
// return `0x${currencyAmount.raw.toString(16)}`
// }
// const amountOutMin = toHex(trade.minimumAmountOut(slippageTolerance))
// const value = toHex(trade.inputAmount)
const uniswap = await new web3.eth.Contract(abi, "0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D")
const now = moment().unix()
const DEADLINE = now + 60 *20
console.log('Sending...')
let txn = await uniswap.methods.swapExactETHForTokens( 1, path, to, DEADLINE ).send( {
from: account,
gasLimit: 8000000,
gasPrice: web3.utils.toWei('100', 'Gwei'),
value: web3.utils.toWei('1', 'Ether')
})
console.log(`Txn: https://rinkeby.etherscan.io/tx/${txn.transactionHash}`)
}catch(e){
console.log(e)
}
}
module.exports = swap
Transaction results on rinkeby etherscan:
Console:
"Error: Transaction has been reverted by the EVM "

Answer 1

Here is an example of swapping ETH to UNI. I am using ethJS.
const WETH_ADDRESS = "0xc778417e063141139fce010982780140aa0cd5ab";
const UNI_ADDRESS = "0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984";
const path = [WETH_ADDRESS, UNI_ADDRESS];
const ethAmount = ethers.utils.parseEther("0.1");
const nowInSeconds = Math.floor(Date.now() / 1000)
const expiryDate = nowInSeconds + 900;
const txn = await uniswapV2Contract.swapExactETHForTokens(
0,
path,
user.address,
expiryDate,
{
gasLimit: 1000000,
gasPrice: ethers.utils.parseUnits("10", "gwei"),
value: ethAmount
}
)
const res = await txn.wait();
When you call the method swapExactETHForTokens, it would be taking ETH and not WETH. If you would like to swap with WETH, you should call swapExactTokensForTokens.