Tips and Tricks for Optimizing Performance in Vue.js Applications

Do you want to improve the performance of your Vue.js applications? This article will teach you all you need to know about code optimisation and caching solutions.

Minimise the Use of Computed Properties and Watchers to Boost Performance in Vue.js

One of the ways to optimize performance for Vue.js applications is to minimize the use of computed properties and watchers. While useful in some cases, computed attributes and watchers are detrimental to performance when overutilized. The reason for this is that the calculated properties and watchers create additional overheads that may result in useless re-rendering of components. Instead, try to use data properties and methods as often as possible since they are much more performant. Consider employing memoisation so that the outcome of the most expensive computation is cached to avoid unnecessary recalculations. You can optimize your Vue.js apps significantly by reducing unnecessary computed properties and watchers.

One of the powerful tools in Vue.js is Watchers, which has been really helpful, especially when one needs to react to changes in single or multiple reactive properties and perform asynchronous or complex operations in response. Watchers are helpful in cases where your action does not relate directly to the data rendering or when you need to coordinate updates between many properties. Understanding when and how to use a watcher will significantly improve the performance of your Vue.js applications.

       watch(data, (newData, oldData) => {
         // Perform some action when 'data' changes
         console.log(`Data changed from ${oldData} to ${newData}`);
         // You can make asynchronous requests here
       });

Computed properties are ideal for deriving values based on other reactive properties. Computed properties are cached and automatically updated when their dependencies change. You should use computed properties for derived data or transformations related to rendering.

       const firstName = ref('John');
       const lastName = ref('Doe');

       const fullName = computed(() => `${firstName.value} ${lastName.value}`);

Data methods are your tools for handling actions or events within your component, like user input, DOM manipulations, or method calls. They give you the power to control the logic that isn't directly related to reactivity but is essential for user interactions. Use data methods to wield this power effectively.

       const count = ref(0);

       const increment = () => {
         count.value += 1;
       };

Use Lazy-Loading and Code Splitting to Reduce Initial Load Time

Lazy loading and code splitting are two significant ways of improving performance in Vue.js apps. Lazy loading is the practice of loading only the necessary components and resources when required rather than everything at once. Because only the relevant components are loaded at first, this can significantly minimise the application's initial load time.

Splitting your code entails dividing it into smaller, more manageable portions. This lets you load only the code required for a certain page or functionality rather than the complete application code. Dividing your code can minimise the overall file size and enhance the loading speed of your application. This also benefits code reuse, meaning you can include the component on many pages rather than copying/pasting code.

Lazy Loading Components in Vue.js

Implementing lazy loading in Vue.js is straightforward. You can use the defineAsyncComponent function, a simple yet powerful tool. This function allows you to load a component asynchronously, improving the initial load time of your application by only fetching the component code when needed.

First, create the component you want to lazy load in a separate file. For example, create a file named LazyLoadedComponent.vue for a component you want to load lazily.

<template>
    <div>
    <!-- Your component's template -->
    </div>
</template>

<script>
// Your component's script
export default {
    // Component options
};
</script>

In your main Vue component, you can use the defineAsyncComponent function to lazily load the component. Import the function and use it to define your component asynchronously. This function takes a callback that loads the component when it's needed.

<template>
    <div>
    <button @click="loadComponent">Load Lazy Component</button>
    <div v-if="showLazyComponent">
        <LazyComponent />
    </div>
    </div>
</template>

<script>
import { defineAsyncComponent, ref } from 'vue';

// Define the component asynchronously
const LazyComponent = defineAsyncComponent(() => import('./LazyLoadedComponent.vue'));

export default {
    components: {
        LazyComponent, // Register the component
    },
    setup() {
        const showLazyComponent = ref(false);

        const loadComponent = () => {
            // Set showLazyComponent to true when you want to load and display the component
            showLazyComponent.value = true;
        };

        return {
            showLazyComponent,
            loadComponent,
        };
    },
};
</script>

When the loadComponent function is called, it sets the showLazyComponent variable to true, which causes the LazyComponent to be loaded and displayed in the template.

This lazy loading technique helps reduce the initial bundle size of your Vue.js application. It can improve its performance by only loading components when they are used.

Optimise Rendering by Using v-if and v-for Directives Efficiently

When optimizing performance in Vue.js apps, it's crucial to use the v-if and v-for directives effectively. These directives can make a significant impact on your app's performance. The v-if directive allows you to render elements conditionally based on a given condition, while the v-for directive enables you to render an array of objects conditionally. Use them mindfully to ensure your code's performance.

It is important to use these directives efficiently to optimise rendering. For example, instead of using v-if and v-for on the same element, use v-if on a parent container and v-for on a child element. This allows the parent element to be rendered only once while the child components are rendered based on the array.

It's also a good idea to avoid using v-if and v-for on large lists or nested structures, which can cause performance problems. Instead, consider preprocessing the data with computed characteristics or filters to reduce the complexity of rendering.

You may optimise the rendering process in your Vue.js applications and enhance overall efficiency by effectively employing the v-if and v-for directives.

Implement Server-Side Rendering (SSR) for Faster Initial Rendering

Server-side rendering (SSR) is a technique that can dramatically enhance the initial rendering speed of your Vue.js apps. SSR reduces the work required by the client's browser by pre-rendering the Vue components and sending the completely rendered HTML to the client.

Adding SSR can increase your application's perceived performance. The user will see material rendered on the page more quickly, which can result in a better user experience and increased user engagement.

SSR can be implemented in your Vue.js application using frameworks such as Nuxt.js or Vue Server Renderer. These frameworks include tools and utilities to assist you in configuring SSR and managing the server-side rendering process.

With the added configuration and considerations that have to be made server-side, Server-Side Rendering is more complicated than client-side rendering. However, the extra effort might pay off for applications with a big initial rendering payload by bringing better performance.

Utilise Caching Strategies Such as Memoization and Local Storage

These caching solutions speed up your Vue applications by reducing the data that needs to be fetched or processed. Memoization is the standard caching technique that memoizes the results of expensive function calls and returns the cached result when the same inputs are provided again.

This is easily achievable in Vue.js using either the Lodash library or by writing your caching method. You can cache the results of computationally expensive processes to avoid recalculations, increasing your application speed altogether.

Local storage allows you to store data on the client's browser, meaning you would not need to fetch data from a server upon subsequent visits. You can achieve local storage caching for your Vue.js app using the browser's local storage API or frameworks like Vuex.

Example of Using Vuex For Caching Data in Vue.js

Here's an example of how Vue 3 Composition API and Vuex can be used for data caching. If you haven't done so already, you must install vuex with the command npm install vuex.

We first need to create a module to handle data caching called a Vuex store.

// store/modules/cache.js

const state = {
  cachedData: {},
};

const mutations = {
  setCache(state, { key, data }) {
    state.cachedData[key] = data;
  },
};

const actions = {
  cacheData({ commit }, { key, data }) {
    commit('setCache', { key, data });
  },
};

const getters = {
  getCachedData: (state) => (key) => state.cachedData[key] || null,
};

export default {
  namespaced: true,
  state,
  mutations,
  actions,
  getters,
};

Now, let's create a Vue 3 Composition API component that uses the Vuex store to cache and retrieve data:

<template>
    <div>
    <h2>Data Caching Example</h2>
    <button @click="fetchAndCacheData">Fetch Data</button>
    <p v-if="cachedData">{{ cachedData }}


    </div>
</template>

<script>
import { ref } from 'vue';
import { useStore } from 'vuex';

export default {
    setup() {
    const store = useStore();
    const cachedData = ref(null);

    const fetchAndCacheData = async () => {
        // Check if data is already cached
        const cached = store.getters['cache/getCachedData']('exampleData');

        if (cached) {
        cachedData.value = cached;
        } else {
        // Simulate fetching data
        const response = await fetchDataFromApi();

        // Cache the data in the Vuex store
        store.dispatch('cache/cacheData', {
            key: 'exampleData',
            data: response,
        });

        cachedData.value = response;
        }
    };

    const fetchDataFromApi = () => {
        return new Promise((resolve) => {
        setTimeout(() => {
            resolve('Fetched data from the API');
        }, 1000);
        });
    };

    return {
        cachedData,
        fetchAndCacheData,
    };
    },
};
</script>

We must register the Vuex store in your main Vue 3 application file.

// main.js
import { createApp } from 'vue';
import App from './App.vue';
import store from './store';

const app = createApp(App);
app.use(store);
app.mount('#app');

You can now use this component in your application. When you click the "Fetch Data" button, the component checks if the data is already cached in the Vuex store. If it's not cached, it fetches the data and caches it.

Monitor Performance in Vue.js Application

Monitoring the performance of a Vue.js application is essential to ensure that your app runs smoothly and efficiently. You can use various tools and techniques to monitor and improve the performance of your Vue.js application.

Browser DevTools are powerful tools for monitoring the performance of your Vue.js application. You can use them to inspect network requests, check the rendering performance, analyse memory usage, and identify potential issues.

The Performance tab in DevTools allows you to record and analyse performance profiles. This can help you identify slow JavaScript code, layout thrashing, and other bottlenecks in your app.

Use the Network tab to monitor network requests, check for unnecessary requests, and optimise resource loading.

The Memory tab helps you detect memory leaks and excessive memory usage in your application.

You can install the Vue DevTools browser extension for Chrome or Firefox. In the case of Vue applications, special options are offered by Vue DevTools. You can inspect component hierarchies, states, and events within it. Especially helpful in tracking component lifecycle and optimizing reactivity.