Evaluate this in the DevTools console:

var arr = [];
console.log(arr);
arr.push(1);

Click on the array with the triangle to expand it.

Actual output:
Array(0)
- 0: 1

Expected output
Array(1)
- 0: 1

Since the properties for logged objects are fetched upon first expansion, the expanded title "Array(0)" should also be computed on first expansion and reflect the number of properties underneath.