Let's say you are using console.log.

console.log(foo);

And something like this is being returned.

[object Object]

This means that foo (in this example) is JSON or a dictionary that contains key value pairs. JSON.stringify can be used to convert the JSON or dictionary object into a string so you can see structure of the object.

console.log(JSON.stringify(foo));

Which may return something like this.

{"hello": "world"}

Or if you know the structure of the object, you can reference a particular key in the object like this.

console.log(foo.hello)

Or like this.

console.log(foo['hello'])

Let's say a POST request is being made in the foo function.

async function foo() {
  try {
    const response = await fetch(`https://api.example.com/api/v1/sandbox`, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ greeting: "Hello World" }),
    });

Here is how you should be able to parse the request in a get route.

app.get("/api/v1/sandbox", async (req, res) => {
  const jsonParse = JSON.parse(JSON.stringify(req.body))
  console.log(jsonParse.greeting);
}