Input of Information into Javascript using terminal

Question

I want to take the output of a c++ program and input it into the stdin of a javascript file. However I have been unable to push anything into the stdin using the method...

node example.js < test.txt

because I get the following errors.

example.js:35

stdin.setRawMode( true );

TypeError: undefined is not a function

at Object. (example.js:35:7)

at Module._compile (module.js:460:26)

at Object.Module._extensions..js (module.js:478:10)

at Module.load (module.js:355:32)

at Function.Module._load (module.js:310:12)

at Function.Module.runMain (module.js:501:10)

at startup (node.js:129:16)

at node.js:814:3

The offending code appears to be as below. It works fine during normal input, however crashes in the above scenario.

var stdin = process.stdin;
stdin.setRawMode( true );
stdin.resume();
stdin.setEncoding( 'utf8' );
stdin.on( 'data', function( key ){
//do stuff based upon input

Has anyone encountered this, or any ideas about how to fix it? Or another way of going about this problem?

Actually, scratch that. I'm seeing the same behavior when redirecting stdin. Investigating further. — Rob Raisch
– Rob Raisch, Commented Mar 10, 2015 at 2:54

Rob Raisch · Accepted Answer · 2015-03-10 03:07:45Z

4

When running your program with redirected stdin, you're connected to a ReadStream, not a TTY, so TTY.setRawMode() isn't supported.

setRawMode() is used to set a tty stream so that it does not process its data in any way, such as providing special handling of line-feeds. Such processed data is referred to as being "cooked".

Standard node ReadStreams are, by definition, already "raw" in that there is no special processing of the data.

So, refactor your code without the call to setRawMode() and it should work fine.

answered Mar 10, 2015 at 3:07

Rob Raisch

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Just Jake · Accepted Answer · 2015-03-10 03:05:23Z

0

This is how I process data from STDIN in Node:

function readStream(stream, callback) {
  var data = '';
  stream.setEncoding('utf-8');
  stream.on('data', onData);
  stream.on('end', onEnd);

  function onData(chunk) {
    data += chunk;
  }

  function onEnd() {
    stream.removeListener('end', onEnd);
    stream.removeListener('data', onData);
    callback(data);
  }
}

The error message in your questions (the "undefined is not a function") error means you were trying to call a method on stdin that doesn't exist. I couldn't find a mention of setRawMode in a cursory scan of the docs. Perhaps you are using an outdated API? I recall having to unpause STDIN (old-style streams) is deprecated.

answered Mar 10, 2015 at 3:05

Just Jake

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