contentEditable отступ( tab)

let divs = document.getElementsByClassName("test"); 
[].forEach.call(divs, function(item) { 
  item.addEventListener("keydown", function(e) { 
    if (e.keyCode === 9) { 
      e.preventDefault(); 
      let div = this; 
      let selection = div.ownerDocument.defaultView.getSelection(); 
      let range = selection.getRangeAt(0); 
      let tab = document.createTextNode("\u00a0\u00a0\u00a0\u00a0"); 
      range.insertNode(tab); 
      range.setStartAfter(tab); 
      range.setEndAfter(tab); 
      selection.removeAllRanges(); 
      selection.addRange(range); 
    } 
  }) 
})

<div class='test' id="editor" contentEditable='true'> Some text</div>