Pardon me for my poor english. What I am trying to achieve is:
I am learning node JS developing a crypto currency exchanger as a homework project where user can deposit ERC-20 token and Ethereum. I am generating unique ethereum deposit address for every user, where they can deposit ERC-20 token and ethereum. but after sometime I want to move the received ethereum and ERC-20 token to another address (cold wallet). Now my question is, if someone only send ERC-20 token to the address and no etherum, then how I'll get ethereum to pay as gas fee to transfer the received ERC-20 token to cold wallet ? If suppose, I am first paying etherum (for gas fee) from cold address to the user address, and then using that etherum to transfer received ERC-20 token, will it work at mass level ? means if 10000 users do the same thing at the same time, will not it create a problem ? or is there any better solution for this ? please help
