Improve / make more efficient a Javascript snippet

I wrote this Javascript snippet for a Polymer fronted and it works without issues.

Are there any ways that you could suggest to make it more efficient / shorter?

        var expandedItems = this.shadowRoot.querySelectorAll('expandable-item');
        
        for (var i = 0; i < expandedItems.length; ++i) {
          if (expandedItems[i].hasAttribute("expanded")){
            expandedItems[i].getElementsByClassName("expandable-icon")[0].setAttribute("icon", "arrow:chevron-open-down");
          } else {
            expandedItems[i].getElementsByClassName("expandable-icon")[0].setAttribute("icon", "arrow:chevron-open-right");
          }
        }

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