anyone know an easy way to get the name, symbol and decimals of any erc20 token (by address) with web3js?

I'm not sure how easy you think this is, but you can just check it with web3.eth.call

I don't see name or decimals among the functions in standard erc20 interface: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v2.5.0/contracts/token/ERC20/IERC20.sol

they're not part of the standard. but many contracts implement those. of course if the contract doesn't have such information then you can't get it