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grader.js
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grader.js
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#!/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 rest = require('restler');
var HTMLFILE_DEFAULT = "index.html";
var CHECKSFILE_DEFAULT = "checks.json";
var URL_DEFAULT = "http://google.com";
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 cheerioUrl = function(response) {
return cheerio.load(response);
};
var loadChecks = function(checksfile) {
return JSON.parse(fs.readFileSync(checksfile));
};
var checkHtmlFile = function(htmlfile, checksfile) {
$ = cheerioHtmlFile(htmlfile);
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 checkUrl = function(response,checksfile){
$ = cheerioUrl(response);
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({});
};
var restResponse = function(result, response) {
if (result instanceof Error) {
console.error('Error: ' + util.format(response.message));
} else {
var checkJson = checkUrl(response,program.checks);
var outJson = JSON.stringify(checkJson, null, 4);
console.log(outJson);
}
};
if(require.main == module) {
program
.option('-f, --file <html_file>', 'Path to index.html', clone(assertFileExists))
.option('-c, --checks <check_file>', 'Path to checks.json', clone(assertFileExists), CHECKSFILE_DEFAULT)
.option('-u, --url <website url>', 'URL of the website', URL_DEFAULT)
.parse(process.argv);
if (program.file){
var checkJson = checkHtmlFile(program.file, program.checks);
var outJson = JSON.stringify(checkJson, null, 4);
console.log(outJson);
}
else {
rest.get(program.url).on('complete',restResponse);
//var outJson = program.url;
}
} else {
exports.checkHtmlFile = checkHtmlFile;
}