[Ethereum] How to read a data sent to the Smart Contract

Byte-per-byte comparisons. Conversions needed. reddit link is dead. Why do you need to access msg.data directly?

EDIT: Convert a uint256 from calldata bytes to a proper uint256 in Solidity: https://gist.github.com/anonymous/a734a5d299ffa7b5a834

EDIT: The typing system and posting rules on this site are super weird. Anyways that works. It should always return true.

After adding an event like SquareComputed (see How to get values returned by non constant transaction functions?) and web3.js Contract Events example

var event = myContractInstance.MyEvent({valueA: 23} [, additionalFilterObject])

// watch for changes
event.watch(function(error, result){
  if (!error)
    console.log(result);
});

this would lead to code like:

var event = myContractInstance.SquareComputed({});

// watch for changes
event.watch(function(error, result){
  if (!error)
    resolve({
        primary_address: config.ethConfig.primary_address,
        numSquare : result  // need to access the properties of result to obtain the actual square 
    })
  event.stopWatching();
});

Do the above before myContractInstance.squareNumber.sendTransaction. The resolve({numSquare:...}) in the original code should be moved to inside the watch as above.

Other web3.js APIs such as web3.eth.filter can also be used (see How do I retrieve the Voted events from The DAO).

This questions asks "how exactly do I structure my web3js code, to get the value returned (10*10) from the solidity function squareNumber()", otherwise for an overview see What is the difference between a transaction and a call?.