How to implement a dark mode in Vue.js

Implementing a dark mode in a Vue.js application involves toggling between light and dark themes and updating the styles accordingly. Here's a step-by-step guide on how to implement a simple dark mode toggle in a Vue.js project:

1. Setup Vue Project: Ensure you have Vue.js installed. If not, you can create a new Vue project using Vue CLI:

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   vue create my-dark-mode-app
   cd my-dark-mode-app
   

2. Install a CSS-in-JS Library: To easily switch between light and dark themes, you can use a CSS-in-JS library like stylus or sass. Install the preferred one:

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   # For Sass
   npm install node-sass sass-loader --save-dev
   
   # For Stylus
   npm install stylus stylus-loader --save-dev
   

3. Create Styles: Create separate styles for light and dark themes. You can use a simple approach by creating two separate style files, for example, light-theme.scss and dark-theme.scss:

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   /* light-theme.scss */
   body {
     background-color: #fff;
     color: #333;
   }
   

   scssCopy code
   /* dark-theme.scss */
   body {
     background-color: #333;
     color: #fff;
   }
   

4. Toggle Theme: Create a method in your Vue component to toggle between light and dark themes. You can use a class on the body element to switch styles. Here's an example in a Vue component:

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   <!-- App.vue -->
   <template>
     <div>
       <button @click="toggleTheme">Toggle Theme</button>
       <div :class="{ 'dark-theme': isDarkMode }">
         <!-- Your application content goes here -->
       </div>
     </div>
   </template>
   
   <script>
   export default {
     data() {
       return {
         isDarkMode: false,
       };
     },
     methods: {
       toggleTheme() {
         this.isDarkMode = !this.isDarkMode;
       },
     },
   };
   </script>
   
   <style lang="scss">
   /* Add your global styles here */
   .dark-theme {
     @import "@/styles/dark-theme.scss";
   }
   </style>
   

5. Add Styles to the Main Entry File: Import the main style file in your main entry file (e.g., main.js or main.ts):

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   // main.js
   import Vue from 'vue';
   import App from './App.vue';
   import './styles/main.scss'; // Import your main style file
   
   Vue.config.productionTip = false;
   
   new Vue({
     render: h => h(App),
   }).$mount('#app');
   

6. Test: Run your Vue application and test the toggle button to switch between light and dark themes.

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   npm run serve
   

This is a basic example, and you might need to adjust it based on your application structure and styling preferences. Additionally, you can use Vue's provide and inject functions or a state management library like Vuex for a more organized state management, especially if the dark mode state needs to be shared across multiple components.