Basic programming on Solidity

Question

I'm reading through the documentation here https://solidity.readthedocs.io/en/latest/introduction-to-smart-contracts.html

and it says "In order to listen for this event, you would use..."

Coin.Sent().watch({}, '', function(error, result) {
     if (!error) {
        console.log("Coin transfer: " + result.args.amount +
        " coins were sent from " + result.args.from +
        " to " + result.args.to + ".");
        console.log("Balances now:\n" +
        "Sender: " + Coin.balances.call(result.args.from) +
        "Receiver: " + Coin.balances.call(result.args.to));
     }
})

Now, this is not part of the contract itself, so where would I run this code?

Answer 1

It's a JavaScript code. You can use this javascript as client (web3j) to observe events