And the way this works is that there's a crawling agent that can go to the World Wide Web and retrieve pages, through just a computer program.

This is the first step towards our crawler, which will crawl a set of webpages, finding all of the links that can be found from a seed page.

Here's one for HTML, and here's another one for JavaScript.

Another super common kind of tag is the anchor tag, which is used to add hyperlinks to webpages.

Their servers are probably on fire, because it's Twitter.

Here I've typed it out.

We get the same set of commands now being read from the saved commands variable.

This function call tells it which string to break up.

Otherwise, it would be run away bold.

Let's see how things are going towards that goal.

Let's go and see Pex in action.

All right. Infinite loops, those are no fun at all.

So for Question 1, we want to see that you understand how web pages are constructed and what a web crawler will do.

The way that works remember is if I click history, we can see the previous versions of this page.

We say Oh, it's something like http.google.com.index.html.

Google made MapReduce famous building their indices for the web.

Let me show you a more complicated example. We'll see how it plays out in real life.

Let's see some examples.

We'll try a more interesting test.

And now what we want to do is use these regular expressions, together these token definitions to break up a Web page.

W'll go through the specific requirements in the instructor comments, but the important thing the first thing is if you type in a URL that doesn't exist, you go to an edit page.

So it doesn't look kind of ugly and black and white.

If someone had written this program in JavaScript and put it in the middle of a web page, our web browser would loop forever and never actually render the resulting web page.

like this string containing (55).

Create and edit presentations for slideshows, meeting and Web pages by using Impress.

Our web browser will accept as input HTML and JavaScript, the primary languages of the web, and use that to produce an image of the web page.

Another topic that I would like to address is malformed HTML.

This is the recorded commands, namely open, save, and quit.

Let's see whether we get a nice listing together with the covered lines.

This will save us from having to call get_page twice. Get_page is fairly expensive.

If you have a big program like a web browser and you try it on 10 web pages and it seems good, that is not a proof that it's always going to work perfectly in the future, but it does give you more confidence than only trying it on 1 web page.

So typically, programs are very big and accept an infinite set of inputs.

So this should write out 120 and then true.

In each item, like in the unordered list is defined with an LI tag.

Congratulations, you've now got a working search engine.

The exclamation mark often means factorial in mathematics.

What we have built so far is a web crawler.

So there's this collective decision making that's going on.

In unit 3, we're going to talk about breaking up tokens and seeing if they match a particular structure, seeing if they're in the language of a formal grammar that describes all of JavaScript or all of web pages.

Well, we've talked quite a bit about interpretation.

Millions of deaf and hard of hearing viewers require subtitles to access video.

I'm going to now export this as a style sheet.

You can add a comment containing English text to explain what a program should be doing.

For example, in this case maybe all of that adds up to 6, and that's what we'll display in our resulting webpage.

Networks are all about abstraction.