Error: Unable to set attribute because the property is undefined in the onLoad function

Can anyone help troubleshoot this error?

List of included files:

<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();

Everything renders correctly without errors on load, but there's an issue when clicking on it:

https://i.sstatic.net/qgSEu.jpg

javascriptbootstrap-4dropdownsemantic-uipopper.js

Answer №1

We encountered a similar issue with the html code below:

<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 choose one</option>
    <option class="dropdown-item" value="type1">Carrier</option>
    <option class="dropdown-item" value="type2">Shipper</option>
</select>

After removing data-toggle="dropdown" from the <select> tag, the error disappeared without affecting the dropdown functionality. Although the reason behind this solution is unclear, it managed to solve the issue. Perhaps it is caused by a conflict of some sort? In any case, this workaround could potentially help others facing a similar problem.

Answer №2

I encountered a similar issue in Bootstrap 4.x when my dropdown menu did not share the same parent as the dropdown button I was utilizing.

<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>

The reason for the issue is that the dropdown.js code searches for the menu using the following code:

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

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

To resolve this problem, ensure that the menu and the toggle share the same parent element.

<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>

Answer №3

Exploring CSS Frameworks

Before delving into CSS frameworks, it is crucial to decide between Bootstrap 4 and Semantic-UI. Mixing both can lead to confusion and complexity in your project.

Bootstrap 4

If you opt for Bootstrap 4 for its simplicity and beginner-friendly nature, ensure you include jQuery and Popper.js in your code. These scripts are essential for Bootstrap's components to function properly.

As mentioned in Bootstrap's documentation:

Many components in Bootstrap require JavaScript for their functionality. jQuery, Popper.js, and Bootstrap's JavaScript plugins are necessary for these components to work.

Dropdown

For Dropdowns in Bootstrap, make sure to refer to the documentation:

Dropdowns rely on Popper.js for dynamic positioning and viewport detection. Include popper.min.js before Bootstrap’s JavaScript or use bootstrap.bundle.min.js / bootstrap.bundle.js which includes Popper.js. However, in navbars, Popper.js is not required for dropdown positioning.

Once you have chosen your CSS framework, setting up Dropdowns correctly becomes easier. Additionally, exploring Semantic-UI's documentation on Dropdowns can provide a valuable perspective.

Distinguishing NodeJS Environment from Browser JavaScript Environment

It seems you are installing your scripts via npm, but it's unclear if this is your intention. To clarify:

npm acts as a package manager for Node.js packages.

If you aim to keep simplified versions of packages in local folders like 

./project_name/javascript/bootstrap.js
or 
./project_name/css/bootstrap.min.css
, you may not necessarily require node_modules at the moment. However, the choice is ultimately yours.

For insights on using Node and JavaScript effectively, check out this discussion on Stack Overflow.

Answer №4

One reason for the error occurring is due to the incorrect placement of elements. Unfortunately, none of the previous solutions were effective for me.

Misplacement Example 1

<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>

Misplacement Example 2

<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>

Correct Placement

<span class="dropdown 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>

Answer №5

After trying to remove data-toggle="dropdown" without success, I found out that Bootstrap 4.x actually requires it for dropdown menus to function properly.

Interestingly, I encountered a related issue where a third-party plugin I was using had a deprecated function called removeAttr. Switching it to prop solved the problem and eliminated the error message.

Answer №6

Prioritize the semanticUI link after the bootstrap one

<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/semantic-ui/dist/semantic.min.css">
<link rel="stylesheet" href="../../node_modules/fullcalendar/dist/fullcalendar.min.css">

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