I have an ArrayBuffer which is mapped to GPU memory called copyBuffer:

const BUFFER_SIZE = 1000;
const stagingBuffer = device.createBuffer({
  size: BUFFER_SIZE,
  usage: GPUBufferUsage.MAP_READ | GPUBufferUsage.COPY_DST,
});
.
.
.
await stagingBuffer.mapAsync(GPUMapMode.READ, 0, BUFFER_SIZE);
const copyBuffer = stagingBuffer.getMappedRange(0, BUFFER_SIZE);
console.log(copyBuffer);

/* Output:
{
   byteLength: 1000,
   detached: false
   ...
   [[Prototype]]: ArrayBuffer
}
*/

As you see detached property of copyBuffer is false which seems correct because I didn’t detach it from GPU memory.

Although when I detach it something odd (in my opinion) happens:

// continue
console.log(copyBuffer);
stagingBuffer.unmap(); // detach here

/* Output:
{
   byteLength: 1000,
   detached: true
   ...
   [[Prototype]]: ArrayBuffer
}
*/

I added one line after console log and even though it is non-blocking (not async-await), console log shows something different – detached is true!

Doesn’t console.log finished before unmap() execution?