is using their own library right? For instance setProperty() is a custom function?

I am learning JS separately and was confused to run into setProperty(). Is that a custom property that has created for the students? I wish they would state this because I would like to differentiate between whats vanilla JS and a library they use.

For instance, console.log() is vanilla JS, but they dont really differentiate.

Im actually more confused because you need to use dot notation when using setProperty I believe.

MDN: CSSStyleDeclaration.setProperty() - Web APIs | MDN uses its own interpreter for the App Lab and Game Lab platforms. If you’d like to use vanilla JS, use,, or

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So they use a custom interpreter or library? For instance, in there is a setScreen().

Is that considered a “function” that is from a library? Or is that something else, I just dont know how to contextualize this to students.

I just call it a built-in function, since it is, well, a function.

It’s an interpreter. You write code that translates into javascript to run. Libraries add on to the already existing code, such as jQuery in regular javascript - all it does is make some of the functions that previously exist more understandable, or easier to read.

tldr; interpreter: translates code, libraries: add onto code

Everyone is saying this. However, an interpreter in other aspects of computer science translates code into machine code, not into a higher-level language usually. Does have documentation for this or anything? doesn’t have its own documentation, but I’ve seen people somewhere else say that is around 400x slower than vanilla JavaScript since it runs on its own interpreter.

Don’t exaggerate. It is 200x slower.

Jeez, sorry. I didn’t know the exact number.

Just kidding. But the guy who wrote the interpreter says 200x.