how to change the backgroung of one button when click the other one

1 var buttons = document.querySelectorAll("button");
2 
3 for (button in buttons) {
4    buttons[button].onclick = function() {
5        console.log('test')
6        buttons.forEach(function(btn){
7          btn.classList.remove('highlight');
8        })
9        this.classList.add('highlight');
10    }
11}