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In short: I am trying to understand the meaning of this TypeError: Failed to execute 'getComputedStyle' on 'Window': parameter 1 is not of type 'Element' The error appears while lunching Mediawiki's VisualEditor, as can be seen here:

http://www.wiki.org.il/index.php?title=new-page&veaction=edit

The error doesn't enables creating new pages or editing the wiki anonymously. However, with the use of a different skin the error disappears:

http://www.wiki.org.il/index.php/Main_Page?useskin=vector

The wiki runs on 1.25alpha.

OpenFox
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6 Answers6

20

I had this same error showing. When I replaced jQuery selector with normal JavaScript, the error was fixed.

var this_id = $(this).attr('id');

Replace: 

getComputedStyle( $('#'+this_id)[0], "")

With:

getComputedStyle( document.getElementById(this_id), "")
Anish
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    getComputedStyle( document.getElementById(this_id)) will not work. getting the same error – agDev Jun 23 '16 at 19:01
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    It could be that at the time your `getComputedStyle(...)` code runs the element with id `this_id` is not actually present in the DOM. If your also dealing with adding/removing elements that is. – Mudlabs Apr 07 '17 at 07:45
4

The error message says that getComputedStyle requires the parameter to be Element type. You receive it because the parameter has an incorrect type.

The most common case is that you try to pass an element that doesn't exist as an argument:

my_element = document.querySelector(#non_existing_id);

Now that element is null, this will result in mentioned error:

my_style = window.getComputedStyle(my_element);

If it's not possible to always get element correctly, you can, for example, use the following to end function if querySelector didn't find any match:

if (my_element === null) return;
Ryszard Jędraszyk
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2

For those who got this error in AngularJS and not jQuery:

I got it in AngularJS v1.5.8 by trying to ng-include a type="text/ng-template" that didn't exist.

 <div ng-include="tab.content">...</div>

Make sure that when you use ng-include, the data for that directive points to an actual page/section. Otherwise, you probably wanted:

<div>{{tab.content}}</div>
Community
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J.D. Mallen
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1

In my case I was using ClassName.

getComputedStyle( document.getElementsByClassName(this_id)) //error

It will also work without 2nd argument " ".

Here is my complete running code :

function changeFontSize(target) {

  var minmax = document.getElementById("minmax");

  var computedStyle = window.getComputedStyle
        ? getComputedStyle(minmax) // Standards
        : minmax.currentStyle;     // Old IE

  var fontSize;

  if (computedStyle) { // This will be true on nearly all browsers
      fontSize = parseFloat(computedStyle && computedStyle.fontSize);

      if (target == "sizePlus") {
        if(fontSize<20){
        fontSize += 5;
        }

      } else if (target == "sizeMinus") {
        if(fontSize>15){
        fontSize -= 5;
        }
      }
      minmax.style.fontSize = fontSize + "px";
  }
}


onclick= "changeFontSize(this.id)"
Gilles-Antoine Nys
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Pushpender Singh
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0

I had the same error on my Angular6 project. none of those solutions seemed to work out for me. turned out that the problem was due to an element which was specified as dropdown but it didn't have dropdown options in it. take a look at code below: 

<span class="nav-link" id="navbarDropdownMenuLink" data-toggle="dropdown"
                          aria-haspopup="true" aria-expanded="false">
                        <i class="material-icons "
                           style="font-size: 2rem">notifications</i>
                        <span class="notification"></span>
                        <p>
                            <span class="d-lg-none d-md-block">Some Actions</span>
                        </p>
                    </span>
                    <div class="dropdown-menu dropdown-menu-left"
                         *ngIf="global.localStorageItem('isInSadHich')"
                         aria-labelledby="navbarDropdownMenuLink">
                                        <a class="dropdown-item" href="#">You have 5 new tasks</a>
                                        <a class="dropdown-item" href="#">You're now friend with Andrew</a>
                                        <a class="dropdown-item" href="#">Another Notification</a>
                                        <a class="dropdown-item" href="#">Another One</a>
                    </div>

removing the code data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" solved the problem.

I myself think that by each click on the first span element, the scope expected to set style for dropdown children which did not existed in the parent span, so it threw error.

Far
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-33

The error message is pretty straightforward: getComputedStyle expects an Element as its first argument, and something else was passed to it.

If what you are really asking for is help with debugging your skin, you should make more of an effort to isolate the error.

Tgr
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