Get gas fee estimation from any method

[StayFoolisj]

Does ethers.js have any function for estimating the gas fee of a transaction?

With this example I'd not expect it to be a real transaction, but rather have an estimation of gas limit / fee denominated in Gwei:

uniswapContract.swapExactTokensForTokens.estimateGas(
    120*(10**18), 
    100*(10**18), 
    [
        '0xce1bffbd5374dac86a2893119683f4911a2f7814', 
        '0x3ee97d514bbef95a2f110e6b9b73824719030f7a'
    ], 
    user.address, 
    1643191704, 
    {'from':user.address}
)

Thanks!

[StayFoolisj]

Found the answer, just use estimateGas. before the method name like this format contractObject.estimateGas.method()here's my code if anyone needs:

/**
 * Gets an estimate for gas limit (units of gas) expressed in Gwei
 * @param {object} dexRouterContract - Contract object of the DEX router 
 * @param {str} tokenInAddress - Address of the input token
 * @param {str} tokenOutAddress - Address of the output token 
 * @param {int} tokenInAmount - Amount of input token denominated in Wei
 * @param {int} tokenOutAmount - Amount of output token denominated in Wei
 * @param {str} userAddress - Address to perform the swap 
 * (PS: Ensure this address has enough of the input and output token as it impacts the gas estimation) 
 * @returns {str} gasLimit - upper gas limit estimation denominated in Gwei
 */
export async function estimateGasLimitForTokenSwap(
        dexRouterContract,
        tokenInAddress,
        tokenOutAddress,
        tokenInAmount,
        tokenOutAmount,
        userAddress,
    ) {
    let now = new Date
    // Uniswap requires a deadline for the swap. 30 minutes from now expressed as milliseconds since epoch 
    const deadline = now.setTime(now.getTime() + (30 * 60 * 1000)) 
    const gasLimit = await dexRouterContract.estimateGas.swapExactTokensForTokens(
        tokenInAmount,
        tokenOutAmount,
        [
            tokenInAddress,
            tokenOutAddress
        ],
        userAddress,
        deadline,
        {
            from: userAddress
        }
    )
    return gasLimit.toString()
}