How to set javascript environment variables

In JavaScript, the concept of environment variables refers to variables defined in the current running environment. In JavaScript, environment variables can be used to store some important configuration information, API keys, database connection strings and other sensitive information. Since this sensitive information cannot be exposed to front-end users, environment variables need to be defined and set in the back-end environment. This article will introduce the specific implementation method of JavaScript environment variables.

1. What are environment variables?

Environment variables refer to variables within the scope of the current operating system variables. In the operating system, the role of environment variables is to share scattered data among a large number of programs, and also to save some important configuration information, such as paths, API keys, database connection strings and other sensitive information. This information cannot be exposed to front-end users, so it should be defined and set in the back-end environment.

2. How to use environment variables in JavaScript

In JavaScript, environment variables can be accessed through the process.env object. process.env is a global variable provided by Node.js. In a Node.js application, it contains all environment variables in the current process, and all Node.js processes can access it.

For example, if we want to access the environment variable DB_URL, we only need to use process.env.DB_URL:

var dbUrl = process.env.DB_URL;

In this example , we use process.env.DB_URL to access the environment variable DB_URL, and then assign it to the variable dbUrl.

3. How to set environment variables in JavaScript

In JavaScript, you can manually set environment variables. In the Web, you can write environment variables to a configuration file called config.js and then reference the file in your application.

In Node.js applications, you can use the dotenv module to set environment variables. The dotenv module helps you load environment variables from a file into a process.env object for use in your application.

For example, we need to set environment variables in the Node.js application:

1. First, we need to install the dotenv package.
npm install dotenv --save

2. Then, we need to load the dotenv package in the application.
require('dotenv').config()

3. Finally, we set the environment variables in the .env file.
DB_URL=xxxxxxx
API_KEY=yyyyyyy

Now, we can use the two environment variables DB_URL and API_KEY in the application:
const dbUrl = process.env.DB_URL;
const apiKey = process.env.API_KEY;

4. How to set different environment variables in different environments

During the development process, we usually have different environments. For example, development environment, test environment and production environment may need to set different environment variables. In order to achieve this purpose, we can use different configuration files to store different environment variables separately.

For example, in different environments, we may need to set different database connection strings, which can be saved in config/development.env, config/production.env, config/test.env and other files. , and then use the dotenv module to load the correct environment variables.

For example, in the development environment, we need to load the environment variables in the config/development.env file:
require('dotenv').config({path:'./config/development.env '});

In the test environment, we need to load the environment variables in the config/test.env file:
require('dotenv').config({path:'./config/test .env'});

In the production environment, we need to load the environment variables in the config/production.env file:
require('dotenv').config({path:'./config /production.env'});

5. Summary

Environment variables in JavaScript are a very useful technology. Using environment variables in development can help us store, share and hide Important sensitive data. In this article, we covered how to define and use environment variables in JavaScript, and how to set different environment variables in different environments. By using the dotenv module and configuration files, we can easily manage and set environment variables, thereby improving development efficiency and security.

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