GetComputedStyle node not working - Is not defined

Question

I'm writing a webscraping script and I'd like to use getComputedStyle() however it doesn't work on node. I get errors saying getComputedStyle is not defined

If I try global.getComputedStyle, it says global.getComputedStyle is not a function

Obviously window doesn't exist on node so I can't use that.

What do I need to use?

function sortElementsByFontSize(elements: any[]): any[]{
    return elements.sort((a, b) => {
        let aFontSize = parseInt(global.getComputedStyle(a)['fontSize']);
        let bFontSize = parseInt(global.getComputedStyle(b)['fontSize']);
        console.log("Comparing: " + aFontSize + " - " + bFontSize);
        if(aFontSize === bFontSize){
            return 0;
        } else {
            return aFontSize > bFontSize ? 1 : -1
        }
    });
}

Answer 1

getComputedStyle() is something that exists in a browser, not in nodejs.

If this wasn't clear to you, nodejs is a Javascript environment and it supports the latest standards for the Javascript language, but it has its own runtime library that supports things like networking and file I/O. Similarly, the browser supports the latest standards for the Javascript language, but has its own runtime library that supports things like getComputedStyle().

Nodejs doesn't do any HTML rendering on its own, doesn't parse or understand CSS, etc...

So, to use a function like getComputedStyle() you have to either run your Javascript in a browser environment or use a library within nodejs that gives you access to an actual browser engine such as Puppeteer which uses the Chromium browser engine to create a browser-environment where you can run some Javascript.