如何在 jrunscript 或 jjs 中访问 stdin（在 win7 上）

Question

i have googled around quite a bit but couldnt find anything that tells me how to get access to the stdin when executing a JS with jrunscript.

it seems not to be possible.

use case: i want to write a little JS script that does a regex-replace for use on the cmd where i would want to pass in text data via piping, eg

>cat file | jrunsscript -f apply-regex.js

... and out comes the result (which i could pipe into a file, etc).

hence, i need to access to the stdin in order to read the what's piped unto jrunsscript.

side note: for this i usually use sed, but there are problems when the regex itself involves quotes in certain cases.

Answer 1

Not sure if this is on topic: http://docs.oracle.com/javase/7/docs/technotes/tools/share/jsdocs/GLOBALS.html

read(prompt, multiline) Reads one or more lines from stdin after printing a prompt

Based on your comment, I think you need to use arguments as shown: https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jrunscript.html

Usage:

jrunscript -f test.js "Hello World"

Get the argument:

document.write(arguments[0]);

Upon more research, you may be able to read via Interactive mode:

jrunscript -f -

Interactive mode, read script from standard input. If this is used, this should be the last -f option

But still not clear if this is what you're looking for exactly.

Answer 2

the workaround thus far is to

1. pipe the input into a file
2. pass tempfile as arg to jsrunscript
3. use JS output as needed

Answer 3

Take a dip in Java.

in file JJS_SAYS_HI.js

//Java-y bit
var br = new java.io.BufferedReader(
    new java.io.InputStreamReader(
            java.lang.System.in,
            java.nio.charset.StandardCharsets.UTF_8)
    );
//JavaScript-y bit
var line = "";
while(br.ready()) {
    line = br.readLine();
    print("JJS says: ${line}");
};

Test the whole mess with a command like: echo Hi! | jjs -scripting JJS_SAYS_HI.js echo Hi! | jjs -scripting JJS_SAYS_HI.js

Output is JJS says: Hi! (on Windows)