JavaScript Console

The DAC Node JavaScript console exposes the full web3 JavaScript Dapp API and further administrative APIs.

Interactive Use: The Console

The dacnode JavaScript console is started with the console or attach node sub-commands. The console subcommands starts the DAC Node and then opens the console. The attach subcommand attaches to the console to an already-running dacnode instance.

dacnode console
dacnode attach

Attach mode accepts an endpoint in case the dacnode is running with a non default ipc endpoint or you would like to connect over the rpc interface.

dacnode attach /some/custom/.dac/gdacnode.ipc
dacnode attach http://191.168.1.1:8545
dacnode attach ws://191.168.1.1:8546

Note that by default the dacnode doesn't start the HTTP and WebSocket servers and not all functionality is provided over these interfaces for security reasons. These defaults can be overridden with the --http.api and --ws.api arguments when the DAC Node is started, or with admin.startRPC and admin.startWS.

If you need log information, start with:

dacnode console --verbosity 5 2>> /tmp/dacnode.log

Otherwise mute your logs, so that it does not pollute your console:

dacnode console 2> /dev/null

Dacnode has support to load custom JavaScript files into the console through the --preload option. This can be used to load often used functions, or to setup web3 contract objects.

dacnode console --preload "/my/scripts/folder/utils.js,/my/scripts/folder/contracts.js"

Non-interactive Use: Script Mode

It's also possible to execute files to the JavaScript interpreter. The console and attach subcommand accept the --exec argument which is a javascript statement.

dacnode attach --exec "eth.blockNumber"

This prints the current block number of a running dacnode instance.

Or execute a local script with more complex statements on a remote node over http:

dacnode attach http://dacnode.example.org:8545 --exec 'loadScript("/tmp/checkbalances.js")'
dacnode attach http://dacnode.example.org:8545 --jspath "/tmp" --exec 'loadScript("checkbalances.js")'

Use the --jspath <path/to/my/js/root> to set a library directory for your js scripts. Parameters to loadScript() with no absolute path will be understood relative to this directory.

You can exit the console by typing exit or simply with CTRL-C.

Caveats

Dacnode now uses the GoJa JS VM which is compatible with ECMAScript 5.1. There are some limitations though:

• Promises and async won't work.

web3.js uses the bignumber.js library. This library is auto-loaded into the console.

Timers

In addition to the full functionality of JS (as per ECMA5), the DAC JSRE is augmented with various timers. It implements setInterval, clearInterval, setTimeout, clearTimeout you may be used to using in browser windows. It also provides implementation for admin.sleep(seconds) and a block based timer, admin.sleepBlocks(n) which sleeps till the number of new blocks added is equal to or greater than n, think "wait for n confirmations".