Chapter 14. Scraping JavaScript

Client-side scripting languages are languages that are run in the browser itself, rather than on a web server. The success of a client-side language depends on your browser’s ability to interpret and execute the language correctly.

While there are hundreds of server-side programming languages, there’s only one client-side programming language. This is because of the difficulty of getting every browser manufacturer to agree on a standard. This is a good thing when it comes to web scraping: the fewer languages there are to deal with, the better.

Other Client-Side Programming Languages

Some readers may take issue with the sentence: “There’s only one client-side programming language.” Technically, languages such as ActionScript and VBScript exist. However, these are no longer supported and, in the case of VBScript, was only ever supported by a single browser. For this reason, they are very rarely seen.

If you want to be pedantic about it, absolutely anyone can make a new client-side programming language! There are likely many of them out there! The only issue is getting widespread support by browsers to make that language effective and put it into use by others.

Some have also argued that CSS and HTML are programming languages in themselves. I agree with this in theory. Lara Schenck has an excellent and entertaining blog post on the subject: https://notlaura.com/is-css-turing-complete/.

However, in practice, CSS and HTML are generally treated as markup ...

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