How to read and write env files?
Original file：
# I am a note ... key1=value1 key2=value2 # I am a note ... I need a function setEnv(key, value).
run setEnv('key1', 'value2')， Let it become：
# I am a note ... key1=value2 key2=value2 # I am a note ... How can I achieve it?
Lets start by creating new project.
mkdir folder_name cd folder_name npm init Then in your project directory install 'envfile' and 'dotenv'. Command for installing envfile is
npm install envfile --save Similarly install dotenv
npm install dotenv --save package dotenv directly reads .env file package envfile is used to parse and stringify the file as required. Create .env file in the project directory with your details.
# I am a note ... key1=value1 key2=value2 # I am a note ... Create a new file with filename.js
After that for getting and setting env variables you can use following code.
const fs = require('fs'); require('dotenv').config() const { parse, stringify } = require('envfile'); const pathToenvFile = '.env'; /** * * @param {string} key * //Function to get value from env */ function getEnv(key) { console.log("Getting value of " + key); console.log(process.env[key]); } //Calling the function getEnv getEnv("key1"); /** * * @param {string} key * @param {string} value * //Function to set environment variables. */ function setEnv(key, value) { fs.readFile(pathToenvFile, 'utf8', function (err, data) { if (err) { return console.log(err); } var result = parse(data); result[key] = value; console.log(result); fs.writeFile(pathToenvFile, stringify(result), function (err) { if (err) { return console.log(err); } console.log("File Saved"); // Can be commented or deleted }) }); } //Calling the function setEnv setEnv('key1', 'value2'); After this run your file using
node filename.js You can get your desired output.
Initial .env file
# I am a note ... key1=value1 key2=value2 # I am a note ... After running program
key1=value2 key2=value2 Yes your comments gets deleted.
You can use the envfile module as described here.
const fs = require('fs'); const envfile = require('envfile'); const envPath = 'pathToEnvFile/.env'; let parsedFile = envfile.parseFileSync(envPath); parsedFile.NEW_VAR = 'newVariableValue'; fs.writeFileSync(envPath, envfile.stringifySync(parsedFile)); Something like this：
function setEnv(envText, key, value) { if (!envText) { return; } const rp = new RegExp(`${key}=(.*?)\\s`); let result = envText.replace(rp, (m, $1) => { return m.replace($1, value); }); if (!rp.test(result)) { result += `\n${key}=${value}`; } return result; } console.log( setEnv( `# I am a note ... key1=value1 key2=value2 # I am a note ...`, 'key1', 'value2', ), );But this doesn't work:
setEnv( `# I am a note ... key1=value1 key2=value2`, 'key2', 'value1', ) setEnv( `# I am a note ... key1key2=value1 key2=value2`, 'key2', '2222', )
=and write the raw value to it. there is no such thing as escaping in .env files. i see no reason in editing the files with node tho. for reading i usually use npmjs.com/package/dotenv