What is the most common cause of the 'Cannot read properties of undefined (reading 'forEach) error?

The most common cause of the «Cannot read properties of undefined (reading „forEach“)» error is trying to iterate over an undefined or null array or object. www.webdevtutor.net

To avoid this error, make sure that the array or object you are trying to iterate over is defined and initialized properly. www.webdevtutor.net

Other common causes:

• Async operations. www.webdevtutor.net If you are working with asynchronous code, make sure to handle promises or callbacks appropriately to avoid accessing undefined values. www.webdevtutor.net
• Accessing an array index that doesn't exist. bobbyhadz.com frontendscript.com The error often occurs when trying to access an empty array at an index that doesn't exist, which returns undefined. bobbyhadz.com
• Assigning the output of a function that doesn't return anything to a variable. bobbyhadz.com Many built-in methods that mutate an object in place return undefined. bobbyhadz.com