How can I get any Json object to the javascript lambda aws sdk?

Just started using AWS, and I’m trying to create a lambda function using javascript that I call the JSON objects in there.
To do that it’s used JSON.parse() to convert a JSON object or string into a Javascript object.
Example:

let s = '{"hello":"world"}';
let obj = JSON.parse(s);

But what I’m trying to do is to call any JSON object and not to declare with the let function, but to call any object that is on JSON.
Would appreciate any response

Thank you!