grader.js

#!/usr/bin/env node

/* grader.js automatically grade files for the presence of specified HTML tags/attributes */

var fs = require('fs');
var program = require('commander');
var cheerio = require('cheerio');
var rest = require('restler');
var HTMLFILE_DEFAULT = "index.html";
var CHECKSFILE_DEFAULT = "checks.json";

var assertFileExists = function(infile) {
  var instr = infile.toString();
  if(!fs.existsSync(instr)) {
    console.log("%s does not exist. Exiting.", instr);
    process.exit(1); // http://nodejs.org/api/process.html#process_process_exit_code
  }
  return instr;
};

var cheerioHtmlFile = function(htmlfile) {
  return cheerio.load(fs.readFileSync(htmlfile));
};

var loadChecks = function(checksfile) {
  return JSON.parse(fs.readFileSync(checksfile));
};

var checkHtmlFile = function(htmlfile, checksfile) {
  return workCheerio(cheerioHtmlFile(htmlfile), checksfile);
};

var checkUrlPath = function(htmlfile, checksfile) {
  return workCheerio(cheerio.load(htmlfile), checksfile);
  
}

var workCheerio = function(cheerios, checksfile) {
  $ = cheerios;
  var checks = loadChecks(checksfile).sort();
  var out = {};
  for(var ii in checks) {
    var present = $(checks[ii]).length > 0;
    out[checks[ii]] = present;
  }
  return out;

}

var clone = function(fn) {
  // Workaround for commander.js issue.
  // http://stackoverflow.com/a/6772648
  return fn.bind({});
};

if(require.main == module) {
  program
    .option('-c, --checks <check_file>', 'Path to checks.json', clone(assertFileExists), CHECKSFILE_DEFAULT)
    .option('-f, --file <html_file>', 'Path to index.html', clone(assertFileExists), HTMLFILE_DEFAULT)
    .option('-u, --url <url>', 'Url for html file')
    .parse(process.argv);

  if(program.url) {
    rest.get(program.url).on('success', function(urlContents) {
      var checkJson = checkUrlPath(urlContents, program.checks);
      var outJson = JSON.stringify(checkJson, null, 4);
      console.log(outJson);
    });
  } else {
      var checkJson = checkHtmlFile(program.file, program.checks);
      var outJson = JSON.stringify(checkJson, null, 4);
      console.log(outJson);
  }
} else {
  exports.checkHtmlFile = checkHtmlFile;
}