Fetch the API streams

I wanted to try the elegance of the API you created, and I am happy what it provides , the thing is … .it works with curl but trying to use it with fetch I saw that I am dealing with streams I hope someone can help me understand why streams?
how to retrieve first meaningful result here is the code:

fetch(
     `https://deep-index.moralis.io/api/v2/${process.env.contractAddress}/function?chain=${process.env.chain}&function_name=${function_name}`,
     {
       method: 'POST',
       headers: {
         Accept: 'application/json',
         'Content-Type': 'application/json',
         'X-API-Key': process.env.MORALIS_API_KEY
       },
       body: JSON.stringify({
         abi: abi,
         params
       })
     }
   )
     .then(response => response.body)
     .then(body => {
       const reader = body.getReader()

       reader.read().then(({ value, done }) => {
         const result = Utf8ArrayToStr(value)
         console.log(result)
         if (result) {
           resolve(result)
         }
       })
     })

it should work somehow, as it is only a http request