Borislav Hadzhiev
Tue Oct 19 2021·2 min read
Photo by Praveesh Palakeel
The "Cannot set property 'disabled' of null" error occurs for 2 reasons:
disabled
property on a null
value (DOM element that doesn't
exist).Here's an example of how the error occurs.
const button = null; // ⛔️ Cannot set properties of null (setting 'disabled') button.disabled = true;
To solve the "Cannot set property 'disabled' of null" error, make sure the
id
you're using to access the element exists in the DOM. The error often
occurs after providing a non-existent id
to the getElementById
method.
const button = document.getElementById('does-not-exist'); console.log(button); // 👉️ null // ⛔️ Cannot set properties of null (setting 'disabled') button.disabled = true;
We passed a non-existent id
to the getElementById
method and got a null
value back.
Setting the
disabled
property on a null
value causes the error.
To solve the "Cannot set property 'disabled' of null" error, place the JS script tag at the bottom of the body tag. The script should run after the DOM elements have been created.
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> </head> <body> <!-- ⛔️ BAD - script is ran before button exists ⛔️ --> <script src="index.js"></script> <button id="btn">Submit</button> </body> </html>
We placed the JS script tag above the code that creates the button
element.
This means that the index.js
file is ran before the button
is created,
therefore we don't have access to the button
element in the index.js
file.
const button = document.getElementById('btn'); console.log(button); // 👉️ null // ⛔️ Cannot set properties of null (setting 'disabled') button.disabled = true;
The JS script tag should be moved to the bottom of the body, after all of the DOM elements it needs access to.
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> </head> <body> <button id="btn">Submit</button> <!-- ✅ GOOD - button already exists ✅ --> <script src="index.js"></script> </body> </html>
Now, the index.js
file has access to the button
element.
const button = document.getElementById('btn'); console.log(button); // 👉️ button#btn // ✅ Works button.disabled = true;
The "Cannot set property 'disabled' of null" error occurs when trying to set the
disabled
property on a null
value.
To solve the error, run the JS script after the DOM elements are available and make sure you only set the property on valid DOM elements.