Node.js program does not stop reading from stdin

Question

I'm trying to read user input from stdin, in my case, two inputs entered on separate lines. However, when I run the following code (node program.js), it allows me to enter the first value, then I click enter and type in the second value, but when I click enter, it does not run the rest of my program. How do I tell it to stop reading and proceed?

process.stdin.resume();
process.stdin.setEncoding("ascii");
var input = "";
process.stdin.on("data", function (chunk) {
    input += chunk;
});

process.stdin.on("end", function () {  
    lines = input.split("\n");
    var numVals = lines[0];
    process.stdout.write(numVals + "\n");
    var vals = lines[1];
    process.stdout.write(vals+"\n");
});

Added process.on('SIGINT', function(){ console.log('Got SIGINT. Press Control-D to exit.'); }); and now I can stop it with Ctrl+C followed by Ctrl+D, but it prints D — thehme
– thehme, Commented Mar 31, 2015 at 1:42

gregnr · Accepted Answer · 2015-03-29 23:53:00Z

3

Readable Streams expect an EOT (End of transmission) character before it triggers an "end" event. In bash this can be done using CTRL+D. If you want to explicitly stop after 2 line breaks, try this:

process.stdin.resume();
process.stdin.setEncoding("ascii");

var input = "";

process.stdin.on("data", function (chunk) {

    input += chunk;

    var lines = input.split("\n");

    //If there have been 2 line breaks
    if (lines.length > 2) {

        //Stop reading input
        process.stdin.pause();

        //Process data
        var numVals = lines[0];
        process.stdout.write(numVals + "\n");

        var vals = lines[1];
        process.stdout.write(vals+"\n");
    }
});

You are re-inventing the wheel a bit though. Line input is typically handled using the readline or prompt modules.

answered Mar 29, 2015 at 23:53

gregnr

1,2728 silver badges11 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

thehme Over a year ago

Thanks. I actually took pieces from the api site. I added the SIGINT and I can Ctrl+C, followed by Ctrl+D and the rest of my script runs. I will try your recommendation though because the above edit actually makes it print D for some reason.

Collectives™ on Stack Overflow

Node.js program does not stop reading from stdin

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related