How is Google analytics gtag supposed to work in a SPA?

Question

From what I can tell, how google recommends to set up gtag, it's a function that is always pushing more variables onto an array:

window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}

Following the docs on how to use it in a SPA, it seems I'm actually creating a memory leak.

gtag('config', 'GA_TRACKING_ID', {'page_path': '/new-page.html'});
console.log('window.dataLayer', window.dataLayer);

My console shows that every time I navigate to a new page the window.dataLayer array gets larger.

I'm assuming there's something I'm not understanding, because I doubt that Google wants me to create a memory leak in my app, but I'm stumped now.

Answer 1

The size of the dataLayer is capped at 300 (FIFO style) currently.

That's not currently documented and likely to change in the future. But the limit is there exactly to avoid blowing up memory in case repeated events happen inside the same page.