$ 大括号内

Question

I am going through a tutorial, and the author has written a line of code in a GET response through a query string. They write the $ inside the curly brackets without any backticks.

Here is the line of code:

Product.find({ '_id':{$in:items}}).exec({err,docs}=>{ return res.status(200).send(docs) })

I have no idea what exactly is happening.

Answer 1

$ is a valid character in variable names. Eg

let x = 5;
let $ = 6;
let x$8_$$ = 7;
let obj = {$: 8, $$$__$sf93$: 9};

In your snippet, they're using $in as the key in an object literal. Ie, let's say items = [1,2,3] , then the param to Product.find is {'_id': {'$in': [1, 2, 3]}} .