How to Identify Code Is Running on Client or Server in Vue.js

Introduction

In Vue.js, determining whether your code is running on the client or server can be important, especially in server-side rendering (SSR) scenarios. The ability to distinguish between client and server-side execution is crucial in Vue.js development, particularly in scenarios involving server-side rendering (SSR). In this article, we explore methods to identify the runtime environment within Vue.js applications. By examining the presence of the window object for client-side execution and the process object, specifically process.server, for server-side execution, developers can tailor their code to suit the respective environments. This capability empowers developers to create more versatile and robust Vue.js applications capable of seamless execution across diverse runtime environments. Through practical examples and insights, this article equips developers with the knowledge needed to navigate the nuances of client and server-side execution in Vue.js.

Client-Side

To check if your code is running on the client-side in a Vue.js application, you can simply check if the window object is defined. The window object is available in browser environments but not in Node.js environments.

if (typeof window !== 'undefined') {
  // Code is running on the client
  console.log('Running on the client');
} else {
  // Code is not running on the client
  console.log('Not running on the client');
}

Server-Side

In server-side rendering (SSR) scenarios with Vue.js, you may need to determine if your code is executing on the server-side. You can check if the process object exists, which is available in Node.js environments.

if (typeof process !== 'undefined' && process.server) {
  // Code is running on the server
  console.log('Running on the server');
} else {
  // Code is not running on the server
  console.log('Not running on the server');
}

Example in Vue.js Component

Here's how you can use these checks in a Vue.js component:

export default {
  mounted() {
    if (typeof window !== 'undefined') {
      console.log('Running on the client');
    } else {
      console.log('Running on the server');
    }
  }
}

By incorporating these checks into your Vue.js application, you can ensure that your code behaves appropriately based on the runtime environment, whether it's running on the client or server.

Summary

Identifying whether code is executing on the client or server side is essential in Vue.js, especially in server-side rendering (SSR) contexts. In a Vue.js application, you can determine the runtime environment by checking for the presence of the window object, which indicates client-side execution, or the process object, specifically process.server, which indicates server-side execution. This distinction allows developers to conditionally handle code execution based on the environment, ensuring compatibility and appropriate behavior across client and server environments. By incorporating these checks into Vue.js components or SSR setups, developers can build more robust and adaptable applications suited for diverse runtime environments.