node.js: readSync from stdin?

Question

Is it possible to synchronously read from stdin in node.js? Because I\'m writing a brainfuck to JavaScript compiler in JavaScript (just for fun). Brainfuck supports a read o

Answer 1

An updated version of Marcus Pope's answer that works as of node.js v0.10.4:

Please note:

• In general, node's stream interfaces are still in flux (pun half-intended) and are still classified as 2 - Unstable as of node.js v0.10.4.
• Different platforms behave slightly differently; I've looked at OS X 10.8.3 and Windows 7: the major difference is: synchronously reading interactive stdin input (by typing into the terminal line by line) only works on Windows 7.

Here's the updated code, reading synchronously from stdin in 256-byte chunks until no more input is available:

var fs = require('fs');
var BUFSIZE=256;
var buf = new Buffer(BUFSIZE);
var bytesRead;

while (true) { // Loop as long as stdin input is available.
    bytesRead = 0;
    try {
        bytesRead = fs.readSync(process.stdin.fd, buf, 0, BUFSIZE);
    } catch (e) {
        if (e.code === 'EAGAIN') { // 'resource temporarily unavailable'
            // Happens on OS X 10.8.3 (not Windows 7!), if there's no
            // stdin input - typically when invoking a script without any
            // input (for interactive stdin input).
            // If you were to just continue, you'd create a tight loop.
            throw 'ERROR: interactive stdin input not supported.';
        } else if (e.code === 'EOF') {
            // Happens on Windows 7, but not OS X 10.8.3:
            // simply signals the end of *piped* stdin input.
            break;          
        }
        throw e; // unexpected exception
    }
    if (bytesRead === 0) {
        // No more stdin input available.
        // OS X 10.8.3: regardless of input method, this is how the end 
        //   of input is signaled.
        // Windows 7: this is how the end of input is signaled for
        //   *interactive* stdin input.
        break;
    }
    // Process the chunk read.
    console.log('Bytes read: %s; content:\n%s', bytesRead, buf.toString(null, 0, bytesRead));
}