The vue3 process.env.XXX environment variable does not take effect

Problem: When using process.env.XXX, the value of the environment variable cannot be obtained:

axios.defaults.baseURL = process.env.VUE_APP_BASE_API;

solve:

One: In the .env.development and .env.production environment configuration files in the project root directory, the value of NODE_ENV= development must be consistent with the startup configuration --mode of the package.json file

//.env.development
NODE_ENV=development
VUE_APP_BASE_API=/api
VUE_APP_BASE_URL=http://localhost:8081/
VUE_APP_PROXYURL=http://localhost:8080/

"scripts": {
        "serve": "vue-cli-service serve",
        "dev": "vue-cli-service serve --mode development",
        "prod": "vue-cli-service serve --mode production",
    },

Two: The variable names in the .env.development and .env.production environment configuration files must start with VUE_APP_