Observable

Paul Buffa

Learn how to make your own Observable notebooks with these guided walkthroughs.


Hands-on Tutorials

Array and Date are not a valid Javascript types. Both are "object":

```
const date = new Date();
console.log(typeof date); // "object"
const arr = [1, 2, 3];
console.log(typeof arr); // "object"
```

Removing Array and Date, we could add the rest of the types Javascript supports: Null, Undefined, BigInt and Symbol.

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#primitive_values

Victor Jolissaint

Thanks for the feedback! 

+1 to adding Null and Undefined. I'll add those in. 

I hear you, though for a beginners walkthrough of JavaScript, I think its okay to call them types of variables. For example: https://www.w3schools.com/js/js_arrays.asp they call them type of variable, and note that they are technically objects later on. We don't even get into typeof in this. 

Arrays are often called types of variables or data structures. This is more of a casual classification, which speaks to the audience we're writing this for. The general idea is that different types of variables can be treated differently, and there are operations you can run on an array that you can't on an integer.

Sounds good to me, I agree that we can think of Array or even Date as types but I wanted to make sure we don't "trick" people in developing the wrong mental model for these.

+1 I added a note the arrays section about this, and will update the phrasing here. Thanks again!

The last few cells are a bit confusing. How is this: `myNewerArray = myData.map(d => ({...d, date: new Date() }) )` a method that allows me to get all the values from the original array `myData`? I thought `myData` is just a set of objects with name and city for 6 people?