I am fetching data from my backend using fetch function and it returns a readableStream as response’s body. How can I extract the data in that readable stream?
I’ve tries using res.json method, but it returns undefined.
Here’s my fetch call –

fetch('/playground',{
      method: 'POST',
    }).then(function(res){
      res.json()
    }).then(data => console.log(data))

it returns undefined in the console.

Here’s the code from node.js server

router.route('/playground')
.post((req,res)=>{
    res.send({message: 'Hello from backend'})
})

I was expecting it to give me output as an object with key value pair as

{
  message: "Hello from backend"
}

but it returns undefined