Haml to html in realtime

haml2html.js

// usege: node haml2html <file>
var sys  = require('util'),
    fs   = require('fs'),
    http = require('http'),
    exec = require('child_process').exec

var argv   = process.argv,
    target = argv[2]

if(!target){
    console.error('usage: ' + argv.join(' ') + ' <filename>')
    process.exit(1)
}

monitor(target, function(cur, prev){
    haml2html(target)
});

/**
 * Monitor a file changes
 * @param {String} file path of html file
 * @param {Function} callback callback when file was changed
 */
function monitor(file, callback) {
    fs.stat(file, function(e, stat){
        if(e){ throw e }
        if(!stat.isFile()) {
            console.error(file + ' is not file.')
            process.exit(1)
        }

        fs.watchFile(file, { interval: 500 }, callback)
    })
}

/**
 * Convert to haml to html using ruby haml
 * NOTE: gem install haml
 * @param {String} file target html file path
 */
function haml2html(file) {
    var output = target.replace('.haml', '.html'),
        cmd = 'haml -f html5 --trace ' + file + ' ' + output

    exec(cmd, function(e, stdout, stderr) {
        if(e){ console.error(e) }
        console.log('updated ', output)
    })
}