grader.js

#!/usr/bin/env node
/*
Automatically grade files for the presence of specified HTML tags/attributes.
Uses commander.js and cheerio. Teaches command line application development
and basic DOM parsing.

References:

 + cheerio
   - https://github.com/MatthewMueller/cheerio
   - http://encosia.com/cheerio-faster-windows-friendly-alternative-jsdom/
   - http://maxogden.com/scraping-with-node.html

 + commander.js
   - https://github.com/visionmedia/commander.js
   - http://tjholowaychuk.com/post/9103188408/commander-js-nodejs-command-line-interfaces-made-easy

 + JSON
   - http://en.wikipedia.org/wiki/JSON
   - https://developer.mozilla.org/en-US/docs/JSON
   - https://developer.mozilla.org/en-US/docs/JSON#JSON_in_Firefox_2
*/

var fs = require('fs');
var program = require('commander');
var cheerio = require('cheerio');
var restler = require('restler');
var HTMLFILE_DEFAULT = "index.html";
var CHECKSFILE_DEFAULT = "checks.json";
var URL_HTMLFILE_DEFAULT = "urlIndex.html";
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 assertUrlExists = function(fileUrl) { return fileUrl;};

var urltoHtmlFile = function(fileUrl) {
    var instr = fileUrl.toString();
    var fileData = "";
    var event = 0;
    restler.get(instr).on('complete', function(result) {
                        if (result instanceof Error) {
                            console.log("Error : " + result.message);
                            process.exit(1);
                        } else {
                            fileData = result;
                            console.log("File Data : " + fileData);
                        }
                      });
    wait_for_signal(event,5000); 
    console.log(" after Signal : " + fileData);
    return fileData;
};


var cheerioHtmlFile = function(fileData) {
    return cheerio.load(fileData);
};

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

var checkHtmlFile = function(fileData, checksfile) {
    
    $ = cheerioHtmlFile(fileData);
    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), "")
        .option('-u, --url <html_file_url>', 'url path to index.html', clone(assertUrlExists), "")
        .parse(process.argv);
    var checkJson = ""
     if (program.file) {
        console.log("File option is selected");
        checkJson = checkHtmlFile(fs.readFileSync(htmlfile), program.checks);
        var outJson = JSON.stringify(checkJson, null, 4);
        console.log(outJson);var outJson = JSON.stringify(checkJson, null, 4);
        console.log(outJson);

    }else if (program.url) {
//        console.log("URL option is selected");
  //      console.log(" URL : " + program.url);
        restler.get(program.url).on('complete', function(result) {
                        if (result instanceof Error) {
                            console.log("Error : " + result.message);
                            process.exit(1);
                        } else {
                            checkJson = checkHtmlFile(result, program.checks);
                            var outJson = JSON.stringify(checkJson, null, 4);
                            console.log(outJson);

                        }

                      });
 
    } else {
        console.log("Please provide right options");
     }
} else {
    exports.checkHtmlFile = checkHtmlFile;
}