Web Scraping with Node.js

Cheerio Selectors

Investigating the range of selectors offered by Cheerio

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Selectors

Web scraping with Cheerio uses selectors to specify the data we want. When we pulled the h2 tags from the page in the previous activity we created a selector:

    // Search for the elements we want
    selection = $('h2')

The selector could then be used to pull the data from the page:

    // Add the elements to the list
    selection.each((i,el) => {
      text = $(el).text()
      results.push({country:text})        
    })

Cheerio has a number of selectors and selector patterns for different scenarios.

Here is a list of examples of the most common selector scenarios:

Selector	Action
`$('.')`	Select all elements on the page
`$('div')`	Select all div elements on the page
`$('h1, h2')`	Select all h1 and h2 elements on the page
`$('div > p')`	Select all p elements directly under a div (children)
`$('div p')`	Select all p elements under a div either directly or indirectly (find)
`$('#xyz')`	Select all elements with an id of xyz
`$('.pqr')`	Select all elements with the CSS class (style) pqr
`$('title')`	Select the title element

There are also some functions that we can apply to a selector:

Function	Purpose
`selector.children()`	Select all elements directly under the selector
`selector.children('p')`	Select all p elements directly under the selector
`selector.find('tr')`\|Select all tr elements directly or indirectly under the selector
`selector.first()`\| Select the first direct child of the elements in the selector
`selector.last()`\| Select the last direct child of the elements in the selector
`selector.each(fn)`\| Loop through all elements in the selection and apply the function fn

On the next page we will explore these selectors and functions.

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