How could I print event logs and stopWatching() within the node script?

Question

I have following script. I want to do stopWatching after the event-logs are printed and automatically kill the running node, but via script I was not able to achive it.

run.js:

Web3 = require("web3");
web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
exports.LogJob = function( blkNum ) {
    var event = myContractInstance.LogJob({}, { fromBlock: blkNum, toBlock: blkNum });
    event.watch( function (error, result) {
        console.log( JSON.stringify(result ) );                 
    });
    sleep.sleep(10);     //without those two lines it prints logs and pauses.
    event.stopWatching();//
}

ret = Log.Job( 100000 ); //I cannot return since watching is on.

Running: node run.js after printing logs does not kill itself and pauses like in a while(). Please note that if I have some other calls after calling LogJob() it always gives its output after everything is printed. So I can't return the output and do some operations.

If I do stopWatching() after 10 seconds within the function, now it does not print anything.

[Q] How could I print event logs and stopWatching() within the node script?

Answer 1

Please note that this works if and only if there is a log on the scanned blocks otherwise it pauses again. When we new input is feed in on the latest block process.exit() successfully.

I come up with following solution, it works and fixes the hanging issue:

run.js:

var fs = require('fs');
fs.unlinkSync("/tmp/test.txt");
Web3   = require("web3");
web3   = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

address="0x..." 
abi=[...]
var myContractInstance  = web3.eth.contract(mylib.abi).at(mylib.address);

var event = myContractInstance.LogJob({}, { fromBlock: blkNum, toBlock: 'latest' });
event.watch( function (error, result) {
    fs.appendFile( "/tmp/test.txt", JSON.stringify(result) + '\n', function(err) { 
       process.exit();
    });
}

After running node run.js we can find the output as follows:

cat /tmp/test.txt