How to Modify CSS Pseudo-Element Styles with JavaScript Without 'Uncaught TypeError: Cannot read property 'style' of null'?

Modifying CSS Pseudo-Element Styles with JavaScript

While attempting to adjust the color and visibility of the scrollbar using JavaScript, it's common to encounter the error "Uncaught TypeError: Cannot read property 'style' of null". This occurs because websites have disabled scrolling by default, causing the scrollbar elements to not exist.

To work around this limitation, you can employ the CSS Vars technique. This method involves defining fallback values in your CSS and dynamically manipulating them using CSS variables in JavaScript.

In your CSS, define the scrollbar styles with fallback values as follows:

#editor {
  --scrollbar-background: #ccc;
}

#editor::-webkit-scrollbar-thumb:vertical {
  /* Fallback */
  background-color: #ccc;
  /* Dynamic value */
  background-color: var(--scrollbar-background);
}

Then, in your JavaScript, modify the variable that controls the scrollbar background color:

document.getElementById("#editor").style.setProperty('--scrollbar-background', localStorage.getItem("Color"));

This approach allows for dynamic modification of scrollbar styles without encountering "null" errors. Keep in mind that this technique may not be supported in all browsers, so consider graceful degradation for older browsers.

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