Deploy contracts on Ethereum and reliable get the contract address

createContract.js

// -> Soldity
// **********

// Your Soldity contract
event Created(bytes32 indexed identifier);

contract MyContract {
    function MyContract(bytes32 identifier) {
        Created(identifier);
    }
    ...
}



// -> JavaScript
// *************

// create contract
var MyContract = web3.eth.contract(abi);
// the identifier you pass need to be UNIQUE per contract, so you can reliably detect the log generated by your "Created" event
var myContractInstance = MyContract.new('0x16bd7d60bc08217d2e78d09658610a9eb6de22df8b587fdca9e980fafc4ecfcc', {from: ..., data: ..., gas: 123456})
var createdAtBlock = web3.eth.blockNumber;


// listen for created log/event
var Created = web3.eth.filter({
    topics: [null, '0x16bd7d60bc08217d2e78d09658610a9eb6de22df8b587fdca9e980fafc4ecfcc'],
    fromBlock: createdAtBlock,
    toBlock: 'latest'
});
Created.watch(function(error, log) {
    if(!error) {
        console.log('Contract created on '+ log.address);
        
        myContractInstance.address = log.address;

        // remove filter
        Created.stopWatching();

        // watch for the last next 12 blocks if the code is still at the address
        var filter = web3.eth.filter('latest');
        filter.watch(function(e, blockHash){
            if(!e) {
                var block = web3.eth.getBlock(blockHash);

                // check if contract stille exists, if show error to the user
                if((block.number - createdAtBlock) < 12 &&
                    web3.eth.getCode(myContractInstance.address).length > 2) {
                    alert('Oh no the contract is gone!');
                } else if (block.number - createdAtBlock > 12) {
                    filter.stopWatching();
                }
            }
        });
    }
});

Is the check .length == '0x' in line 49 really correct?

there is a ) too much at line 31 :)

This gist is outdated use:
web3.contract(abiArray).new({}, function(e, res){...})

See here for more: https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethcontract

Should line 49 be length <= 2 ?

Is there a way to generate this kind of identifiers at execution time?

I created an example here using Web3.js 1.0.0 Beta 27 and trying to implement the Created event that @frozeman used https://github.com/ltfschoen/geth-node/blob/master/scripts/main.js
It doesn't work yet because it appears the unlockAccount() function hasn't been implemented yet. See web3/web3.js#1264