Your HTML and JS are correct. Did you forget the <script> and </script> tags needed around the JS?

<form id="dynamicForm">
  <div id="inputContainer">
    <input type="text" name="inputField[]">
  </div>
  <button type="button" id="addInput">Add Input</button>
  <button type="button" id="removeInput">Remove Input</button>
</form>
<script>
const addButton = document.getElementById('addInput');
const removeButton = document.getElementById('removeInput');
const inputContainer = document.getElementById('inputContainer');

addButton.addEventListener('click', function() {
  const newInput = document.createElement('input');
  newInput.type = 'text';
  newInput.name = 'inputField[]';
  inputContainer.appendChild(newInput);
});

removeButton.addEventListener('click', function() {
  const inputs = inputContainer.getElementsByTagName('input');
  if (inputs.length > 1) {
    inputContainer.removeChild(inputs[inputs.length - 1]);
  } else {
    alert('At least one input field is required!');
  }
});
</script>