Examples of correct usage scenarios and error scenarios for vue2 global mixing

The use of global mixins in Vue.js needs to be carefully considered as it affects all components. Here are some examples of correct and incorrect usage scenarios:

Correct usage scenario:

1. Global tool methods:

   // 正确的使用场景
   Vue.mixin({
     methods: {
       $formatDate: function (date) {
         // 格式化日期的全局方法
       }
     }
   });
   

   In this example, we have added a $formatDate method, which is available in all components and is used to format dates.

2. Global status management:

   // 正确的使用场景
   Vue.mixin({
     data: function () {
       return {
         globalState: {
           user: null,
           isAuthenticated: false
         }
       };
     }
   });
   

   In this example, we added a data object named globalState that can be accessed in all components.

Wrong usage scenario:

1. Globally change a component’s lifecycle hook:

   // 错误的使用场景
   Vue.mixin({
     created: function () {
       console.log('This will be called in every component\'s created hook');
     }
   });
   

   In this example, we try to globally change the created hook for all components, which can lead to problems that are difficult to debug and understand because every component will execute the same logic.

2. Introduce global state without namespace:

   // 错误的使用场景
   Vue.mixin({
     data: function () {
       return {
         user: null,
         isAuthenticated: false
       };
     }
   });
   

   In this example, we try to add user and isAuthenticated directly in each component's data, which may lead to confusion and conflicts in the global state .

In general, global mixins should be used with caution. It applies to some global functions that are shared throughout the application, such as tool methods, global state, or some common configuration. If you only want to use some functionality in a specific component, it's better to use local mixins or introduce the functionality separately.