Remix Ethereum where goes the contract?

Question

I don't understand where actually the smart contract goes, when I click on create under remix.ethereum.org. If I choose for example the Injected Web3, this should publish the contract to the ropsten test net, right? But how can I access the contract then? When I use metamask it injects me the right provider when I use web3.js, but how can I find this contract now, if I don't want to use the injected web3, but manually choose the provider address in web3.js? Can I access the smart contract this way?

Edit: I don't know what should be wrong about my question.I seriously find nothing about how how to connect to a smart contract for example in the ropsten test network without injected web3. Normally you do this in web3.js:

if (typeof web3 !== 'undefined') {
            web3 = new Web3(web3.currentProvider);
        } else {
            // set the provider you want from Web3.providers
            web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
        }
}

But if you don't have an injected web3, then you use the localhost. But I cannot connect then to the smart contract, because it does not know, in which net I actually published the smart contract, right?

Answer 1

Remix has 3 different environment options that can be used to deploy/test Solidity contracts: JavaScript VM, Injected Web3, and Web3 Provider. This option can be changed under the Environment drop down under the Run tab. (It looks like you've got this part...just documenting for completeness).

1. JavaScript VM: This is Remix's own internal sandbox. It does not connect to MainNet, TestNet, or any private network. It's an in-memory blockchain that can be used for simple testing and quick mining.
2. Injected Web3: This is the option to use for the browser plugin (MetaMask). Here, you are telling Remix to defer all control of the blockchain integration to the MetaMask plugin. At this point, MetaMask controls which network you are connecting to. In the plugin, you can connect to MainNet, Ropsten, Rinkeby, etc through Infura's node network. In this case, you're not running a node locally. MetaMask also has a localhost option where you can run your own node locally and MetaMask will send all transactions to it (this local network can be a private network using any node client or you can use a test blockchain like TestRPC).
3. Web3 Provider: This allows you to enter a URL in Remix to connect to the blockchain. The most common setup here is to be running a local node and connecting to it through it's IP/port. This is pretty much the same as using MetaMask's localhost option, but you're just cutting the plugin out of being the middleman. Just like option #2, the network your connected to depends on how you've configured your local node (it can be main, test, private, etc.).

So, "where your smart contract goes" depends on which of the configurations you have set up. Selecting Injected Web3 does not automatically mean your contract is being deployed to Ropsten. It depends on which network you have selected in the MetaMask plugin.

When using MetaMask through Remix, you need to use the plugin to select the appropriate account and confirm/reject transactions. Selecting the account is a bit confusing because Remix doesn't pick up all of the accounts imported into MetaMask. The Account dropdown will only have the account currently selected in MetaMask. In addition, if you change the account in MetaMask, you have to reload Remix for it to have that account selected in the dropdown. It does NOT automatically detect when the account has changed in MetaMask.

Once the account is properly selected (and assuming you're using an account that holds ether), you can now deploy your contract. Hit Create in Remix and then switch over to the plugin again. There, you should see a pending transaction waiting to approved. Select the transaction, then click Submit.

Transaction list:

Approve/Reject screen:

After submitting, it'll take a few seconds for the transaction to be mined. MetaMask will show when it's completed. That's it! To interact with the contract, you can initiate your transactions through Remix similar to the deployment steps above.