How to write a string to standard output from Javascript

Question

I am interested in a portable way of writing a string to standard output, without implicit newlines added to the end, ideally forcing encoding to UTF-8, that works with either of

jrunscript (from any JDK)
Rhino
node.js

My current code tries to detect where it is running, then uses a platform-specific write method:

  if (typeof process !== "undefined") {     // assume node.js
    var log = function(string) {process.stdout.write(string);};
  }
  else if (typeof println == "undefined") { // assume rhino
    var log = function(string) {java.lang.System.out.write(java.lang.String(string).getBytes("utf-8"));};
  }
  else {                                    // assume jrunscript
    var log = function(string) {java.lang.System.out.print(string);};
  }
  log("X");
  log("Y");

It should result in:

XY

Can this be done better?

For jrunscript, I had been using function print, but that changed its behavior in JDK-8 on behalf of JDK-8021773.

I have similar code in my project. Note that you'll want to test on Nashorn too. (Java 8 bundles Nashorn, not Rhino.) — Seth Tisue
– Seth Tisue, Commented Mar 26, 2014 at 17:03
@SethTisue, thanks for the hint. In fact upgrading JDK to 8 was what got me thinking about this again. Also, Rhino and its (pre-8) JDK flavor already needed to be distinguished to this respect. — Gunther
– Gunther, Commented Mar 26, 2014 at 18:33

mpm · Accepted Answer · 2014-03-19 22:26:27Z

3

I am interested in a portable way of writing a string to standard output, without implicit newlines added to the end, ideally forcing encoding to UTF-8, that works with either of...

there is none,since javascript doesnt have "system apis". JS core is limited and you need to use the api available within the environment javascript engine is running in.

My current code tries to detect where it is running, then uses a platform-specific write method. But I'd rather get rid of that.

that's the only thing you can do.

EDIT : the javascript spec is here : http://es5.github.io/ and it's short,there is 0 notion of standard output or standard input because there is no javascript standard library.

edited Mar 19, 2014 at 22:26

answered Mar 19, 2014 at 17:05

mpm

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1 Comment

Gunther Over a year ago

OK, thanks. So I'll keep my platform distinction code, as shown in the question.

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