node uriChanged.js <URI_GOES_HERE>

uriChanged.js

var request = require('request');

var timer, firstBody, deltaT, t = 0;


var fetchURI = function(uri, cb) {
    request({uri:uri}, function (error, response, body) {
        if (error) {
            cb(error);
        }
        else if (response.statusCode !== 200) {
            cb(t + ': status was ' + response.statusCode);
        }
        else {
            cb(null, body);
        }
    });
    t += deltaT/1000;
};


var testBody = function(err, body) {
    if (err) {
        //clearInterval(timer);
        console.log(err);
    }
    if (!firstBody) {
        firstBody = body;
    }
    else if (body === firstBody) {
        console.log(t + ': hasn\'t changed');
    }
    else {
        clearInterval(timer);
        console.log(t + ': changed!');
    }
};


var scriptName = process.argv[1];
var args = process.argv.slice(2);
var uri = args[0];
deltaT = args[1];
deltaT = (deltaT ? parseInt(deltaT, 10) * 1000 : 2000);

if (!uri) {
    console.log('Syntax: node ' + scriptName + ' <uri goes here> [<every n seconds>]');
}
else {
    console.log('Checking every ' + (deltaT/1000) + ' seconds for changes in URI ' + uri);
    fetchURI(uri, testBody);
    timer = setInterval(function() {
        fetchURI(uri, testBody);
    }, deltaT);
}