588 lines
16 KiB
Markdown
588 lines
16 KiB
Markdown
# cheerio [](http://travis-ci.org/MatthewMueller/cheerio)
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Fast, flexible, and lean implementation of core jQuery designed specifically for the server.
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## Introduction
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Teach your server HTML.
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```js
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var cheerio = require('cheerio'),
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$ = cheerio.load('<h2 class = "title">Hello world</h2>');
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$('h2.title').text('Hello there!');
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$('h2').addClass('welcome');
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$.html();
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//=> <h2 class = "title welcome">Hello there!</h2>
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```
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## Installation
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`npm install cheerio`
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## Features
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__❤ Familiar syntax:__
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Cheerio implements a subset of core jQuery. Cheerio removes all the DOM inconsistencies and browser cruft from the jQuery library, revealing its truly gorgeous API.
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__ϟ Blazingly fast:__
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Cheerio works with a very simple, consistent DOM model. As a result parsing, manipulating, and rendering are incredibly efficient. Preliminary end-to-end benchmarks suggest that cheerio is about __8x__ faster than JSDOM.
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__❁ Insanely flexible:__
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Cheerio wraps around @FB55's forgiving htmlparser. Cheerio can parse nearly any HTML or XML document.
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## What about JSDOM?
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I wrote cheerio because I found myself increasingly frustrated with JSDOM. For me, there were three main sticking points that I kept running into again and again:
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__• JSDOM's built-in parser is too strict:__
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JSDOM's bundled HTML parser cannot handle many popular sites out there today.
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__• JSDOM is too slow:__
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Parsing big websites with JSDOM has a noticeable delay.
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__• JSDOM feels too heavy:__
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The goal of JSDOM is to provide an identical DOM environment as what we see in the browser. I never really needed all this, I just wanted a simple, familiar way to do HTML manipulation.
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## When I would use JSDOM
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Cheerio will not solve all your problems. I would still use JSDOM if I needed to work in a browser-like environment on the server, particularly if I wanted to automate functional tests.
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## API
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### Markup example we'll be using:
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```html
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<ul id="fruits">
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<li class="apple">Apple</li>
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<li class="orange">Orange</li>
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<li class="pear">Pear</li>
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</ul>
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```
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This is the HTML markup we will be using in all of the API examples.
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### Loading
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First you need to load in the HTML. This step in jQuery is implicit, since jQuery operates on the one, baked-in DOM. With Cheerio, we need to pass in the HTML document.
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This is the _preferred_ method:
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```js
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var cheerio = require('cheerio'),
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$ = cheerio.load('<ul id = "fruits">...</ul>');
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```
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Optionally, you can also load in the HTML by passing the string as the context:
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```js
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$ = require('cheerio');
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$('ul', '<ul id = "fruits">...</ul>');
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```
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Or as the root:
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```js
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$ = require('cheerio');
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$('li', 'ul', '<ul id = "fruits">...</ul>');
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```
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You can also pass an extra object to `.load()` if you need to modify any
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of the default parsing options:
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```js
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$ = cheerio.load('<ul id = "fruits">...</ul>', {
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ignoreWhitespace: true,
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xmlMode: true
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});
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```
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These parsing options are taken directly from htmlparser, therefore any options that can be used in htmlparser
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are valid in cheerio as well. The default options are:
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```js
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{
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ignoreWhitespace: false,
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xmlMode: false,
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lowerCaseTags: false
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}
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```
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For a list of options and their effects, see [this](https://github.com/FB55/node-htmlparser/wiki/DOMHandler) and
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[this](https://github.com/FB55/node-htmlparser/wiki/Parser-options).
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### Selectors
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Cheerio's selector implementation is nearly identical to jQuery's, so the API is very similar.
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#### $( selector, [context], [root] )
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`selector` searches within the `context` scope which searches within the `root` scope. `selector` and `context` can be an string expression, DOM Element, array of DOM elements, or cheerio object. `root` is typically the HTML document string.
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This selector method is the starting point for traversing and manipulating the document. Like jQuery, it's the primary method for selecting elements in the document, but unlike jQuery it's built on top of the CSSSelect library, which implements most of the Sizzle selectors.
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```js
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$('.apple', '#fruits').text()
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//=> Apple
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$('ul .pear').attr('class')
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//=> pear
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$('li[class=orange]').html()
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//=> <li class = "orange">Orange</li>
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```
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### Attributes
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Methods for getting and modifying attributes.
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#### .attr( name, value )
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Method for getting and setting attributes. Gets the attribute value for only the first element in the matched set. If you set an attribute's value to `null`, you remove that attribute. You may also pass a `map` and `function` like jQuery.
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```js
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$('ul').attr('id')
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//=> fruits
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$('.apple').attr('id', 'favorite').html()
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//=> <li class = "apple" id = "favorite">Apple</li>
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```
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> See http://api.jquery.com/attr/ for more information
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#### .removeAttr( name )
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Method for removing attributes by `name`.
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```js
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$('.pear').removeAttr('class').html()
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//=> <li>Pear</li>
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```
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#### .hasClass( className )
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Check to see if *any* of the matched elements have the given `className`.
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```js
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$('.pear').hasClass('pear')
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//=> true
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$('apple').hasClass('fruit')
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//=> false
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$('li').hasClass('pear')
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//=> true
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```
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#### .addClass( className )
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Adds class(es) to all of the matched elements. Also accepts a `function` like jQuery.
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```js
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$('.pear').addClass('fruit').html()
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//=> <li class = "pear fruit">Pear</li>
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$('.apple').addClass('fruit red').html()
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//=> <li class = "apple fruit red">Apple</li>
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```
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> See http://api.jquery.com/addClass/ for more information.
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#### .removeClass( [className] )
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Removes one or more space-separated classes from the selected elements. If no `className` is defined, all classes will be removed. Also accepts a `function` like jQuery.
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```js
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$('.pear').removeClass('pear').html()
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//=> <li class = "">Pear</li>
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$('.apple').addClass('red').removeClass().html()
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//=> <li class = "">Apple</li>
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```
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> See http://api.jquery.com/removeClass/ for more information.
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### Traversing
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#### .find(selector)
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Get a set of descendants filtered by `selector` of each element in the current set of matched elements.
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```js
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$('#fruits').find('li').length
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//=> 3
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```
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#### .parent()
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Gets the parent of the first selected element.
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```js
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$('.pear').parent().attr('id')
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//=> fruits
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```
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#### .next()
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Gets the next sibling of the first selected element.
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```js
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$('.apple').next().hasClass('orange')
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//=> true
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```
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#### .prev()
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Gets the previous sibling of the first selected element.
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```js
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$('.orange').prev().hasClass('apple')
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//=> true
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```
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#### .slice( start, [end] )
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Gets the elements matching the specified range
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```js
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$('li').slice(1).eq(0).text()
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//=> 'Orange'
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$('li').slice(1, 2).length
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//=> 1
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```
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#### .siblings()
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Gets the first selected element's siblings, excluding itself.
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```js
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$('.pear').siblings().length
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//=> 2
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```
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#### .children( selector )
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Gets the children of the first selected element.
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```js
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$('#fruits').children().length
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//=> 3
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$('#fruits').children('.pear').text()
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//=> Pear
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```
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#### .each( function(index, element) )
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Iterates over a cheerio object, executing a function for each matched element. When the callback is fired, the function is fired in the context of the DOM element, so `this` refers to the current element, which is equivalent to the function parameter `element`. To break out of the `each` loop early, return with `false`.
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```js
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var fruits = [];
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$('li').each(function(i, elem) {
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fruits[i] = $(this).text();
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});
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fruits.join(', ');
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//=> Apple, Orange, Pear
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```
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#### .map( function(index, element) )
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Iterates over a cheerio object, executing a function for each selected element. Map will return an `array` of return values from each of the functions it iterated over. The function is fired in the context of the DOM element, so `this` refers to the current element, which is equivalent to the function parameter `element`.
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```js
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$('li').map(function(i, el) {
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// this === el
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return $(this).attr('class');
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}).join(', ');
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//=> apple, orange, pear
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```
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#### .filter( selector ) <br /> .filter( function(index) )
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Iterates over a cheerio object, reducing the set of selector elements to those that match the selector or pass the function's test. If using the function method, the function is executed in the context of the selected element, so `this` refers to the current element.
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Selector:
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```js
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$('li').filter('.orange').attr('class');
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//=> orange
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```
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Function:
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```js
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$('li').filter(function(i, el) {
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// this === el
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return $(this).attr('class') === 'orange';
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}).attr('class')
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//=> orange
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```
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#### .first()
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Will select the first element of a cheerio object
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```js
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$('#fruits').children().first().text()
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//=> Apple
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```
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#### .last()
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Will select the last element of a cheerio object
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```js
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$('#fruits').children().last().text()
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//=> Pear
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```
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#### .eq( i )
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Reduce the set of matched elements to the one at the specified index. Use `.eq(-i)` to count backwards from the last selected element.
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```js
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$('li').eq(0).text()
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//=> Apple
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$('li').eq(-1).text()
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//=> Pear
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```
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### Manipulation
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Methods for modifying the DOM structure.
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#### .append( content, [content, ...] )
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Inserts content as the *last* child of each of the selected elements.
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```js
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$('ul').append('<li class = "plum">Plum</li>')
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$.html()
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//=> <ul id = "fruits">
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// <li class = "apple">Apple</li>
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// <li class = "orange">Orange</li>
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// <li class = "pear">Pear</li>
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// <li class = "plum">Plum</li>
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// </ul>
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```
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#### .prepend( content, [content, ...] )
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Inserts content as the *first* child of each of the selected elements.
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```js
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$('ul').prepend('<li class = "plum">Plum</li>')
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$.html()
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//=> <ul id = "fruits">
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// <li class = "plum">Plum</li>
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// <li class = "apple">Apple</li>
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// <li class = "orange">Orange</li>
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// <li class = "pear">Pear</li>
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// </ul>
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```
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#### .after( content, [content, ...] )
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Insert content next to each element in the set of matched elements.
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```js
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$('.apple').after('<li class = "plum">Plum</li>')
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$.html()
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//=> <ul id = "fruits">
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// <li class = "apple">Apple</li>
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// <li class = "plum">Plum</li>
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// <li class = "orange">Orange</li>
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// <li class = "pear">Pear</li>
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// </ul>
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```
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#### .before( content, [content, ...] )
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Insert content previous to each element in the set of matched elements.
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```js
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$('.apple').before('<li class = "plum">Plum</li>')
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$.html()
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//=> <ul id = "fruits">
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// <li class = "plum">Plum</li>
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// <li class = "apple">Apple</li>
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// <li class = "orange">Orange</li>
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// <li class = "pear">Pear</li>
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// </ul>
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```
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#### .remove( [selector] )
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Removes the set of matched elements from the DOM and all their children. `selector` filters the set of matched elements to be removed.
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```js
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$('.pear').remove()
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$.html()
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//=> <ul id = "fruits">
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// <li class = "apple">Apple</li>
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// <li class = "orange">Orange</li>
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// </ul>
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```
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#### .replaceWith( content )
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Replaces matched elements with `content`.
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```js
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var plum = $('<li class = "plum">Plum</li>')
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$('.pear').replaceWith(plum)
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$.html()
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//=> <ul id = "fruits">
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// <li class = "apple">Apple</li>
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// <li class = "orange">Orange</li>
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// <li class = "plum">Plum</li>
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// </ul>
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```
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#### .empty()
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Empties an element, removing all it's children.
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```js
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$('ul').empty()
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$.html()
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//=> <ul id = "fruits"></ul>
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```
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#### .html( [htmlString] )
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Gets an html content string from the first selected element. If `htmlString` is specified, each selected element's content is replaced by the new content.
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```js
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$('.orange').html()
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//=> Orange
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$('#fruits').html('<li class = "mango">Mango</li>').html()
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//=> <li class="mango">Mango</li>
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```
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#### .text( [textString] )
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Get the combined text contents of each element in the set of matched elements, including their descendants.. If `textString` is specified, each selected element's content is replaced by the new text content.
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```js
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$('.orange').text()
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//=> Orange
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$('ul').text()
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//=> Apple
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// Orange
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// Pear
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```
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### Rendering
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When you're ready to render the document, you can use `html` utility function:
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```js
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$.html()
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//=> <ul id = "fruits">
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// <li class = "apple">Apple</li>
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// <li class = "orange">Orange</li>
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// <li class = "pear">Pear</li>
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// </ul>
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```
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If you want to return the outerHTML you can use `$.html(selector)`:
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```js
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$.html('.pear')
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//=> <li class = "pear">Pear</li>
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```
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### Miscellaneous
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DOM element methods that don't fit anywhere else
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#### .toArray()
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Retrieve all the DOM elements contained in the jQuery set, as an array.
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```js
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$('li').toArray()
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//=> [ {...}, {...}, {...} ]
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```
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#### .clone() ####
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Clone the cheerio object.
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```js
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var moreFruit = $('#fruits').clone()
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```
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### Utilities
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#### $.root
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Sometimes you need to work with the top-level root element. To query it, you can use `$.root()`.
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```js
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$.root().append('<ul id="vegetables"></ul>').html();
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//=> <ul id="fruits">...</ul><ul id="vegetables"></ul>
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```
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#### $.contains( container, contained )
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Checks to see if the `contained` DOM element is a descendent of the `container` DOM element.
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## Screencasts
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http://vimeo.com/31950192
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> This video tutorial is a follow-up to Nettut's "How to Scrape Web Pages with Node.js and jQuery", using cheerio instead of JSDOM + jQuery. This video shows how easy it is to use cheerio and how much faster cheerio is than JSDOM + jQuery.
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## Test Coverage
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Cheerio has high-test coverage, you can view the report [here](https://s3.amazonaws.com/MattMueller/Coverage/cheerio.html).
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## Testing
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To run the test suite, download the repository, then within the cheerio directory, run:
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```shell
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make setup
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make test
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```
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This will download the development packages and run the test suite.
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## Contributors
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These are some of the contributors that have made cheerio possible:
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```
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project : cheerio
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repo age : 1 year, 4 months ago
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commits : 416
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active : 118 days
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files : 26
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authors :
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278 Matt Mueller 66.8%
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68 Matthew Mueller 16.3%
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27 David Chambers 6.5%
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15 Siddharth Mahendraker 3.6%
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7 ironchefpython 1.7%
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5 Jos Shepherd 1.2%
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5 Ben Sheldon 1.2%
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2 alexbardas 0.5%
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2 Rob Ashton 0.5%
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1 mattym 0.2%
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1 Chris O'Hara 0.2%
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1 Mike Pennisi 0.2%
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1 Rob "Hurricane" Ashton 0.2%
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1 Sindre Sorhus 0.2%
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1 Wayne Larsen 0.2%
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1 Ben Atkin 0.2%
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```
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## Special Thanks
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This library stands on the shoulders of some incredible developers. A special thanks to:
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__• @FB55 for node-htmlparser2 & CSSSelect:__
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Felix has a knack for writing speedy parsing engines. He completely re-wrote both @tautologistic's `node-htmlparser` and @harry's `node-soupselect` from the ground up, making both of them much faster and more flexible. Cheerio would not be possible without his foundational work
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__• @jQuery team for jQuery:__
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The core API is the best of it's class and despite dealing with all the browser inconsistencies the code base is extremely clean and easy to follow. Much of cheerio's implementation and documentation is from jQuery. Thanks guys.
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__• @visionmedia:__
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The style, the structure, the open-source"-ness" of this library comes from studying TJ's style and using many of his libraries. This dude consistently pumps out high-quality libraries and has always been more than willing to help or answer questions. You rock TJ.
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## License
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(The MIT License)
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Copyright (c) 2012 Matt Mueller <mattmuelle@gmail.com>
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files (the
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'Software'), to deal in the Software without restriction, including
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without limitation the rights to use, copy, modify, merge, publish,
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distribute, sublicense, and/or sell copies of the Software, and to
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permit persons to whom the Software is furnished to do so, subject to
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the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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