how to set textbox value in jquery

Question

How do I properly load the a certain value into a textbox using jquery?Tried the one below but I get the [object Object] as output. Please enlighten me on this,

Answer 1

try

subtotal.value= 5 // some value

proc = async function(x,y) {
  let url = "https://server.test-cors.org/server?id=346169&enable=true&status=200&credentials=false&methods=GET&" // some url working in snippet
  
  let r= await(await fetch(url+'&prodid=' + x + '&qbuys=' + y)).json(); // return json-object
  console.log(r);
  
  subtotal.value= r.length; // example value from json
}

 
Product id: 


Quantity to buy:


Subtotal: