Even though web APIs are becoming more common, it is still common to find a service you want to get data from but can’t because the data is not easily accessible. Web scraping is a last-resort technique that requires programatically extracting the required data from a webpage’s raw HTML. This tutorial will cover how to download and traverse a web page server-side using Node.js and the Zepto.js library.
What we’re Building
Currently, Google does not offer an API to search and browse Android applications. To get around this, we are going to build a command line tool that takes in an app ID, and spits out a bunch of info for that app. Let’s get started by defining our
The first thing we need to do is install the modules that we will need to perform our task. First, create a
package.json file in the root of your project directory that looks like this:
We need three modules to perform our task:
zepto-node, a jQuery-like library for traversing the DOM
domino, to simulate the browser DOM in node (*DOM in No*de)
request, to make HTTP calls
package.json file is ready to go, type
$ npm install in your terminal to download and install the dependencies. Once complete, you should see a new directory called
node_modules/ in the root of your project. This means you are ready to get started. Let’s write some code.
The code for this app needs little explanation. Here is a high level overview of the steps required:
- include required modules
- define the Google Play URL to fetch
- fetch the HTML page
- extract the desired data
The following is a code replay that shows you step-by-step how to create the app. Press play and then hit next after each step to walk through the code:
Here is a sample output from running the command on the ForkJoy app:
Is That It?
Well that was pretty easy wasn’t it? In 30 lines of code we have a command line tool that scrapes information from a web page. So now that you know how easy scraping web pages is with Node.js, what will you build?