[javascript] Javascript Click on Element by Class

So I am writing a script that can be run on a page but I want to click on this element, unfortunately, it does not have an id to get and I am trying to use the .click() function on it, but it doesn't work, here's what I have, anyone know how to fix it? This is the only element in the class also

var classes = document.getElementsByClassName('rateRecipe btns-one-small');
var Rate = classes[0];
Rate.click();

class of my button is "input-addon btn btn-default fileinput-exists"

below code helped me

document.querySelector('.input-addon.btn.btn-default.fileinput-exists').click();

but I want to click second button, I have two buttons in my screen so I used querySelectorAll

var elem = document.querySelectorAll('.input-addon.btn.btn-default.fileinput-exists');
                elem[1].click();

here elem[1] is the second button object that I want to click.

If you want to click on all elements selected by some class, you can use this example (used on last.fm on the Loved tracks page to Unlove all).

var divs = document.querySelectorAll('.love-button.love-button--loved'); 

for (i = 0; i < divs.length; ++i) {
  divs[i].click();
};

With ES6 and Babel (cannot be run in the browser console directly)

[...document.querySelectorAll('.love-button.love-button--loved')]
   .forEach(div => { div.click(); })