What should I do if 'Error in callback for watchers of 'xxx': 'TypeError: Cannot read property 'yyy' of null'' occurs when using vue-router in a Vue application?

In a Vue application, when using vue-router for routing management, you sometimes encounter an error: "Error in callback for watchers of "xxx": "TypeError: Cannot read property 'yyy' of null"". This error usually means there is a problem with the vue-router configuration. Let's solve this problem step by step.

Step one: Check routing configuration

First, we need to check whether the configuration of vue-router is correct, especially when using route nesting, it is easy to make mistakes. We can check in the following ways:

1. Check the naming of the route

When using the routing function, we often need to give each route a name. First, we need to ensure that all route names are unique to avoid reference errors. At the same time we need to confirm whether these names are called correctly, especially when using nested routes.

2. Check the configuration of nested routing

When using nested routing, we need to confirm whether the configuration of the sub-routing is correct. This usually includes whether there is a <router-view> tag in the parent route to load the child route, and whether the child route has the routing path and component name correctly configured.

If there is indeed no problem with the routing configuration, then we need to continue to check if there are other places in the application that may cause the error.

Step 2: Check components and data

If the routing configuration is correct, then there may be a problem with our components or data. We can further check as follows:

1. Check data type

We need to confirm whether the properties or data defined in our component have their types correctly defined and default value.

You can ensure the correctness of the data by adding type and default attributes to the <script> tag. If the data type or default value is not defined correctly, it will lead to errors such as "TypeError: Cannot read property 'yyy' of null".

2. Check the data source

If there are no problems with each data and its type, we also need to check whether the data source and other related component parameters are correct. Especially in complex components or data operations, there may be some details that are prone to errors.

You can observe components and data in Vue Devtools to more intuitively see which component or data has a problem.

Summary

In this article, we introduced the "Error in callback for watchers of "xxx": "TypeError: Cannot read property 'yyy' of when using vue-router null""This kind of error debugging process. We checked routing configuration, component data, and data sources to troubleshoot issues one by one.

I hope that through this article, you can better solve this type of errors and make your Vue application more robust and reliable.

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