require('dotenv').config() 有什么作用？

Question

I know dotenv module is related to environmental variables in nodejs

require("dotenv").config();

and I know that I should put this code in my nodejs server file. but the problem is I didn't understand what config method is actually doing?

    export interface DotenvConfigOptions {

  path?: string;

  encoding?: string;

  debug?: boolean;
}

export interface DotenvConfigOutput {
  error?: Error;
  parsed?: DotenvParseOutput;
}

/**
 * Loads `.env` file contents into {@link https://nodejs.org/api/process.html#process_process_env | `process.env`}.
 * Example: 'KEY=value' becomes { parsed: { KEY: 'value' } }
 *
 * @param options - controls behavior
 * @returns an object with a `parsed` key if successful or `error` key if an error occurred
 *
 */
export function config(options?: DotenvConfigOptions): DotenvConfigOutput;
/** @deprecated since v7.0.0 Use config instead. */
export const load: typeof config;

I looked into config function but I couldn't understand what this code does?

Answer 1

You are looking at the types declaration file, but you should look at the actual config implementation which is written here .

However, the config method takes a .env file path as an argument, it parses it and sets environment vars defined in that file in process.env .

A type declaration file is Typescript concept which allows you to set concrete variable/parameter types for already written Javascript code.