minimalPandocCall.js

const spawn = require('child_process').spawn;
const pandocPath = process.env.PANDOC || 'pandoc';

let args = ['-f', from, '-t', to, '-o', 'output/' + outputFile, inputFile];

let pandoc = spawn(pandocPath, args);

let error = '';
pandoc.on('error', (err) => (throw new Error(err)));

pandoc.stderr.on('data', (data) => error += data);

pandoc.on('close', (code) => {
    if (code !== 0) {
        let msg = 'Pandoc finished with exit code ' + code;
        if (error) {
            msg += ':' + error;
        }
        reject(msg);
    } else {
        console.log('Pandoc finished successfully');
    }
});