Solidity and Blockchain – Why Event Not Visible on Etherscan Transaction List

See How do I get a refund for the amount I paid in excess of 1 ether to 100 The DAO tokens for a working example.

There is an ExtraBalToken contract with a balanceOf(...) method:

contract ExtraBalToken {
    ...
    mapping (address => uint256) public balanceOf;
    ...
}

To access the ExtraBalToken.balanceOf(...) from WithdrawDAO:

contract DAO {
    function balanceOf(address addr) returns (uint);
    ...
}

contract WithdrawDAO {
    DAO constant public mainDAO = DAO(0x5c40ef6f527f4fba68368774e6130ce6515123f2);
    ...

    function withdraw(){
        uint balance = mainDAO.balanceOf(msg.sender);

        if (!mainDAO.transferFrom(msg.sender, this, balance) || !msg.sender.send(balance))
            throw;
    }
    ...
}

If you want to accept the Ether in a smart contract then you should have a fallback function. The fallback function will be called by default when someone transfers ETH to the contract address.

contract Crowdfunder{
   function() Crowdfunder { }
   function() payable {
      contributions.push(
        Contribution({
            amount: msg.value,
            contributor: msg.sender
            })
        );
    totalRaised += msg.value;
    currentBalance = totalRaised;
    LogFundingReceived(msg.sender, msg.value, totalRaised);
    checkIfFundingCompleteOrExpired();
  }
}

In web3js you can send through the normal transaction.

let send = web3.eth.sendTransaction({from:eth.coinbase,to:contract_address, value:web3.toWei(0.05, "ether")});

For further reference regarding fallback function check here.