query selector 2 classes code example

Example 1: javascript get element by multiple class names

document.getElementsByClassName('class1 class2')

Example 2: javascript how to pass more than one selector in querySelectorall

Is it possible to make a search by querySelectorAll using multiple unrelated conditions?

Yes, because querySelectorAll accepts full CSS selectors, and CSS has the concept of selector groups, which lets you specify more than one unrelated selector. For instance:

var list = document.querySelectorAll("form, p, legend");
...will return a list containing any element that is a form or p or legend.