https://teratail.com/questions/25433

HTML

<ul>
  <li class="test">Lorem ipsum dolor</li>
  <li class="test">Fugiat reprehenderit</li>
  <li class="test">Optio maxime est totam</li>
  <li class="test">Labore facere rem architecto</li>
  <li class="test">Assumenda odit unde dicta vel?</li>
</ul>

JavaScript

//document.addEventListener('DOMContentLoaded',function(){
setTimeout(function(){// jsfiddle上では`DOMContentLoaded`は使えない
  var nodes= document.querySelectorAll('.test')
  for(var i=0; i<nodes.length; i++){
    nodes[i].innerHTML= 'New Text'
  }
})