cornet

transform streaming html using css selectors

npm install cornet
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About

The cornet is a brass instrument very similar to the trumpet, distinguished by its conical bore, compact shape, and mellower tone quality. - Wikipedia

This project is demonstrating how to use a couple of my libraries to replace substack/node-trumpet in just a couple of LOC.

Even better, there are some advantages over trumpet:

  • The ammount of usable CSS selectors is increased dramatically thanks to fb55/CSSselect.
  • cornet works as a handler for fb55/htmlparser2, the probably fastest HTML parser currently available for node. And it's much less strict than the sax module used by trumpet.
  • By using the great MatthewMueller/cheerio module, you can do everything with your document that would be possible with jQuery.

Please note that callbacks are fired as soon as an element was retrieved. That means that no content past the element will be available, so cheerio won't find anything, and, as the element is at this time the last child of it's parent, selectors like :nth-last-child won't work as expected.

Install

npm install cornet

Example

var Parser = require("htmlparser2").WritableStream,
    Cornet = require("cornet"),
    minreq = require("minreq"),
    $ = require("cheerio");

var cornet = new Cornet();

minreq.get("http://github.com/fb55").pipe(new Parser(cornet));

cornet.remove("script"); //remove all scripts

//show all repos
cornet.select(".repo_list", function(elem){
    $(elem).find("h3").each(function(i){
        console.log("repo %d: %s", i + 1, $(this).text().trim());
    });
});

//does the same
var i = 0;
cornet.select(".repo_list h3", function(elem){
    console.log("repo %d: %s", ++i, $(elem).text().trim());
});

//sometimes, you only want to get a single element
var onTitle = cornet.select("title", function(title){
    console.log("Page title:", $(title).text().trim());
    cornet.removeLister("element", onTitle);
});

API

cornet(options)

The constructor. options are the same you can pass to fb55/DomHandler.

It's an EventEmitter that emits two events:

  • element is emitted whenever an element was added to the DOM.
  • dom is emitted when the DOM is complete.

cornet#select(selector | fn, cb)

Calls the callback when the selector is matched or a passed function returns true (or any value that evaluates to true).

Internally, listenes for any element event and checks then if the selector is matched.

Returns the listening function, so you can remove it afterwards (as shown in the example above).

cornet#remove(selector | fn)

Removes all elements that match the selector. Also returns the listener.

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