Uncaught TypeError: Cannot read property 'setAttribute' of undefined at Object.onLoad

Question

Any ideas what might be causing this error?

List of my includes:

<link rel="stylesheet" href="../../node_modules/semantic-ui/dist/semantic.min.css">
<link rel="stylesheet" href="../../node_modules/font-awesome/css/font-awesome.min.css">
<link rel="stylesheet" href="../../node_modules/bootstrap/dist/css/bootstrap.min.css">
<link rel="stylesheet" href="../../node_modules/fullcalendar/dist/fullcalendar.min.css">
<script src="../../node_modules/semantic-ui/dist/semantic.min.js"></script>
<script src="../../node_modules/bootstrap/dist/js/bootstrap.bundle.min.js"></script>
<script src="../../node_modules/moment/min/moment.min.js"></script>
<script src="../../node_modules/fullcalendar/dist/fullcalendar.min.js"></script>

HTML Element:

<div class="ui floating dropdown labeled search icon button" style="width: 95%; margin: 0 auto;" id="monthDrop">
    <i class="calendar icon"></i>
    <span class="text">Choose a Month</span>
    <div class="menu">
                <div class="item">January</div>
                <div class="item">February</div>
                <div class="item">March</div>
                <div class="item">April</div>
                <div class="item">May</div>
                <div class="item">June</div>
                <div class="item">July</div>
                <div class="item">August</div>
                <div class="item">September</div>
                <div class="item">October</div>
                <div class="item">November</div>
                <div class="item">December</div>
    </div>
</div>

Script:

$('#monthDrop').dropdown();

It renders fine and everything and no errors on load, just this when I try to click on it:

Answer 1

We ran into the same error with the following html:

<select class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" role="button" v-model="selected" aria-haspopup="true" aria-expanded="false">
    <option disabled value="">Please select one</option>
    <option class="dropdown-item" value="type1">Carrier</option>
    <option class="dropdown-item" value="type2">Shipper</option>
</select>

We tried removing data-toggle="dropdown" from the <select> tag; the error no longer occurred, and the dropdown menu still functioned. Not sure why this works, but it got rid of the error for us. Must be a conflict somehow? Anyways, if someone else is looking for a solution, this workaround may work for them.

Answer 2

I got this same error in Bootstrap 4.x because my dropdown menu did not have the same parent as the dropdown button I was using.

<span class="project-sort-by">Sort by: <a class="dropdown-toggle" href="#" role="button" id="dropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Recent</a></span>

<div class="dropdown-menu" aria-labelledby="dropdownMenuLink">
    <a class="dropdown-item" href="#">Action</a>
    <a class="dropdown-item" href="#">Another action</a>
    <a class="dropdown-item" href="#">Something else here</a>
</div>

This does not work because the dropdown.js code looks for the menu using this code:

  _getMenuElement() {
    if (!this._menu) {
      const parent = Dropdown._getParentFromElement(this._element)

      if (parent) {
        this._menu = parent.querySelector(SELECTOR_MENU)
      }
    }
    return this._menu
  }

To fix this, move the menu so it has the same parent as the toggle.

<span class="project-sort-by">Sort by: 
    <a class="dropdown-toggle" href="#" role="button" id="dropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Recent</a>
    <div class="dropdown-menu" aria-labelledby="dropdownMenuLink">
        <a class="dropdown-item" href="#">Action</a>
        <a class="dropdown-item" href="#">Another action</a>
        <a class="dropdown-item" href="#">Something else here</a>
    </div>
</span>