Angular ERROR TypeError: Cannot read properties of undefined (reading ‘rating’)

Angular ERROR TypeError: Cannot read properties of undefined (reading ‘rating’)

If you are working with Angular and come across the error message ERROR TypeError: Cannot read properties of undefined (reading 'rating'), it means that you are trying to access a property called ‘rating’ on an object that is undefined or null. This error commonly occurs when you are trying to access a property on an object before it has been properly initialized.

Fortunately, there are a few ways to handle this error and prevent it from occurring. Let’s explore some possible solutions:

Solution 1: Use the Safe Navigation Operator

The safe navigation operator, represented by the question mark (?), allows you to safely access properties of an object without throwing an error if the object is undefined or null. By using the safe navigation operator, you can avoid the ‘Cannot read properties of undefined’ error.

Here’s an example of how you can use the safe navigation operator to access the ‘rating’ property:

const rating = obj?.rating;

In the above code snippet, if the obj is undefined or null, the rating variable will be assigned the value of undefined. This prevents the error from occurring.

Solution 2: Check for Object Existence

Another way to handle this error is by checking if the object exists before accessing its properties. You can use an if statement to verify the existence of the object before accessing its properties.

if (obj) {
  const rating = obj.rating;
}

In the above code snippet, the if statement checks if obj exists before accessing the rating property. If obj is undefined or null, the code inside the if block will not be executed, preventing the error.

Solution 3: Use the Nullish Coalescing Operator

The nullish coalescing operator (??) allows you to provide a default value when accessing a property of an object that is null or undefined. This can be useful to avoid the error and provide a fallback value if the property is not defined.

const rating = obj.rating ?? 'No rating available';

In the above code snippet, if obj.rating is null or undefined, the rating variable will be assigned the value 'No rating available'. This ensures that the code does not throw an error and provides a default value instead.

By using one of these solutions, you can handle the ‘Cannot read properties of undefined’ error in Angular and ensure that your code runs smoothly without any unexpected errors.

Remember to always check if an object exists before accessing its properties, or use the safe navigation operator or nullish coalescing operator to handle potential undefined or null values.

Happy coding!