I'm working on a simple webpage project using html, css and javascript. I got a bug, then I located where is the problem:

const myPictures = document.querySelectorAll("div#captcha table img")
console.log(myPictures)
for(let i in myPictures)
    console.log(i)

And there is the console output:

I don't get what's going on here. I thought it will go until 8 only.