querySelectorAll() returns an array of objects with the elements that match the specified group of selectors.
.isArray() will return false because it returns object not array
Syntax:
var elms = document.querySelectorAll('selectors');
- 'selectors' is a string containing one or more CSS selectors separated by commas.
- elms is an array with the selected HTML elements.
Example, gets an Array with the content of LI tags with class='sites', and the tags with class='note' within element with id='dv1', then it displays their content:
Read the blog to better understand the querySelectorAll
https://coursesweb.net/javascript/queryselector-queryselectorall