Node script to convert xml/html MiniBlog post to json/markdown

convert.js

var process = require('process');

var toMarkdown = require('to-markdown');
var xml2js = require('xml2js');

var fs = require('fs')
var path = require('path');

var inputDir = "";
var outputDir = "";

try {
    initialize();
} catch (err) {
    console.error(err);
    console.log('Usage:\nnode convert.js <input directory> <output directory>');
}

fs.readdir(inputDir, function(err, files) {
    if (err) throw err;
    
    files.forEach(function(filename) {
        processFile(filename);
    });
});

function initialize() {
    if (process.argv.length != 4) {
        throw "Invalid arguments";
    }
    
    inputDir = getDirectory(process.argv[2]);
    outputDir = getDirectory(process.argv[3]);
}

function getDirectory(directory) {
    var stats = fs.statSync(directory);
    if (!stats.isDirectory()){
        throw "Provided argument is not a directory";
    }
    
    return directory;
}

function processFile(filename) {
    console.log('Processing ' + filename);
    fs.readFile(getInputFilePath(filename), 'utf8', function (err, content) {
        if (err) throw err;
        
        var parser = new xml2js.Parser({explicitArray: false, mergeAttrs: true});
        parser.parseString(content, function(err, doc) {
            if (err) throw err;
            
            var json = JSON.stringify(convert(doc));
            save(filename, json);
        });
    });
}

var customConverters = [{
    filter: function (node) {
      return node.nodeName === 'PRE' &&
             node.firstChild &&
             node.firstChild.nodeName !== 'CODE';
    },
    replacement: function(content, node) {
      return '\n\n```\n' + node.textContent + '\n```\n\n';
    }
  },
  {
    filter: function (node) {
      return node.nodeName === 'PRE' &&
             node.firstChild &&
             node.firstChild.nodeName === 'CODE';
    },
    replacement: function(content, node) {
      return '\n\n```\n' + node.textContent + '\n```\n\n';
    }
  }];

function convert(doc){
    try {
        if (doc.post.categories != "") {
            doc.post.categories = isArray(doc.post.categories.category) ? doc.post.categories.category : [ doc.post.categories.category ];
        }
        else {
            doc.post.categories = [];
        }
        
        if (doc.post.comments != "") {
            doc.post.comments = isArray(doc.post.comments.comment) ? doc.post.comments.comment : [ doc.post.comments.comment ];
        }
        else {
            doc.post.comments = [];
        }
                
        doc.post.content = toMarkdown(doc.post.content, { converters: customConverters });
        return doc.post;
        
    } catch (err) {
        console.log(doc.post);
        throw err;
    }
}

function isArray(testObject) {
    return testObject &&
	!(testObject.propertyIsEnumerable('length')) &&
	typeof testObject === 'object' &&
	typeof testObject.length === 'number';
}

function save(filename, content) {
    fs.writeFile(getOutputFilePath(filename), content, 'utf8', function(err) {
        if (err) throw err;
    });
}

function getInputFilePath(filename) {
    return path.join(inputDir, filename);
}

function getOutputFilePath(filename) {
    var parts = path.parse(filename);
    return path.join(outputDir, parts.name + '.json');
}