Node.js child process on windows fails for node installed cli apps

test.js

#!/usr/bin/env node

var spawn = require('child_process').spawn;

var child = spawn('npm', ['show', 'yui']);

child.stdout.on('data', function(d) {
	console.log(d + '');
});

child.stderr.on('data', function(d) {
	console.log(d + '');
});

child.on('exit', function(code) {
	console.log('child exited with code', code);
});

how would you modify this to use node-which?