How can I properly load all the texts from all powerpoint slides using PowerPoint Task Plane (JS API)

Question

I'm trying to create an Add-In for powerpoint that can grab all the texts in all powerpoint slides.

At the moment, I am able to grab the texts but i'm not sure if this is a proper way to do it.

const presentation = context.presentation;
const slides = presentation.slides;
slides.load("items/shapes/textFrame/textRange/text");
await context.sync();
// forEach loop thru slides

there isn't a lot of documentation regarding this.

why does using "/" separated strings work but not comma-separated as in the docs?