Vue Global Properties for Theming

Your task is to implement a system for managing global properties within a Vue 3 application using TypeScript. Specifically, you'll create a mechanism to inject global properties that can be accessed and modified from anywhere in your Vue components. This is particularly useful for managing application-wide settings like themes, API URLs, or user authentication states.

Problem Description

You need to create a Vue plugin that allows developers to define and register global properties accessible via app.config.globalProperties. These properties should be reactive, meaning changes to them will automatically update any components that are using them. You will also need to demonstrate how to access and utilize these global properties within a Vue component.

Key Requirements:

1. Vue Plugin: Create a Vue plugin (a function that accepts the app instance).
2. Global Property Injection: The plugin should inject one or more properties into app.config.globalProperties.
3. Reactivity: The injected global properties must be reactive. Changes to these properties should be reflected in all components using them.
4. TypeScript Support: The solution must be written in TypeScript, ensuring type safety for global properties.
5. Component Usage: Demonstrate how to access and display these global properties within a Vue component.

Expected Behavior:

When the plugin is installed, the specified global properties will be available in all Vue components. Modifying these properties from one component should immediately update their display in other components that are using them.

Edge Cases to Consider:

• Overwriting existing global properties: While not explicitly forbidden, consider the implications. The challenge assumes you are defining new global properties.
• Type safety: Ensure that if you define a global property of a certain type (e.g., string), it's treated as such throughout the application.

Examples

Example 1: Basic Theme Color

// main.ts (or your entry point)
import { createApp } from 'vue';
import App from './App.vue';
import globalPropertiesPlugin from './plugins/globalPropertiesPlugin'; // Assuming you create this file

const app = createApp(App);

// Install the plugin with a theme color
app.use(globalPropertiesPlugin, {
  themeColor: 'blue'
});

app.mount('#app');

<!-- MyComponent.vue -->
<template>
  <div :style="{ color: themeColor }">
    The current theme color is: {{ themeColor }}
  </div>
</template>

<script lang="ts">
import { defineComponent } from 'vue';

export default defineComponent({
  name: 'MyComponent',
  // Accessing the global property directly in the template
  // Or you could access it via `this.themeColor` in options API
  // or `(app.config.globalProperties as any).themeColor` in setup
  // but the template binding is the most idiomatic way.
});
</script>

Output:

The text "The current theme color is: blue" will be displayed. If themeColor is changed elsewhere, this text will update accordingly.

Explanation:

The globalPropertiesPlugin injects themeColor into app.config.globalProperties. The MyComponent template directly binds to this property, displaying its value.

Example 2: Multiple Global Properties with Reactivity

// main.ts
import { createApp } from 'vue';
import App from './App.vue';
import globalPropertiesPlugin from './plugins/globalPropertiesPlugin';

const app = createApp(App);

app.use(globalPropertiesPlugin, {
  appName: 'My Awesome App',
  apiUrl: 'https://api.example.com',
  userLoggedIn: false
});

app.mount('#app');

<!-- AnotherComponent.vue -->
<template>
  <div>
    <h1>{{ appName }}</h1>
    <p>API Endpoint: {{ apiUrl }}</p>
    <p v-if="userLoggedIn">Welcome back, user!</p>
    <p v-else>Please log in.</p>
    <button @click="toggleLogin">
      {{ userLoggedIn ? 'Logout' : 'Login' }}
    </button>
  </div>
</template>

<script lang="ts">
import { defineComponent } from 'vue';

export default defineComponent({
  name: 'AnotherComponent',
  methods: {
    toggleLogin() {
      // Access and modify the global property
      (this as any).userLoggedIn = !(this as any).userLoggedIn;
    }
  }
});
</script>

Output:

The component will display the appName, apiUrl, and a login status message. Clicking the button will toggle the login status, and the message will update reactively.

Explanation:

The plugin injects appName, apiUrl, and userLoggedIn. The AnotherComponent displays these. The toggleLogin method directly modifies the reactive userLoggedIn property via this, demonstrating reactivity.

Constraints

• Vue Version: Vue 3.x is required.
• Language: TypeScript must be used for the plugin and component.
• Reactivity: Standard Vue 3 reactivity mechanisms (like ref or reactive from vue) should be used to ensure properties are reactive.
• Plugin Installation: The plugin should be installable using app.use().

Notes

• Consider how you will define the types for your global properties to leverage TypeScript's benefits. You might need to augment Vue's globalProperties interface.
• The problem focuses on injecting initial global properties. Subsequent modifications within the application are expected and are a key part of demonstrating reactivity.
• Think about how to make your plugin flexible enough to accept different initial global properties.