Please , i went details explanation about .innerHTML in js.

Question

Decument.innerHTML

Answer 1

Here you can find some information about it with examples:
https://developer.mozilla.org/en-US/docs/Web/API/Element/innerHTML

Answer 2

It changes an elements text inside. Example:

HTML:
<div id = "d"></div>

JS:
document.getElementById("d").innerHTML = "changed"

HTML after JS runs:
<div id = "d">changed</div>