ErrorOracle
javascript

TypeError: Cannot read properties of null (reading 'length')

Error message

TypeError: Cannot read properties of null (reading 'length')

What broke

The code attempted to read the 'length' property of a variable that is currently null. This typically happens when the variable was expected to hold an object or an array but was not properly initialized.

Why it broke

It broke because the variable was not assigned a valid object or array before the length property was accessed. In JavaScript, attempting to access properties of null results in a TypeError.

How to fix

To fix this, ensure that the variable is properly initialized before accessing its properties. You can add a check to confirm that the variable is not null before trying to read its length.

Code fix

if (myVariable !== null) { console.log(myVariable.length); }

Explained by ErrorOracle

Prevention tip

You can add a check to confirm that the variable is not null before trying to read its length.

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