'nodemon' is not recognized as an internal or external command, operable program or batch file. code example

Example 1: 'NODE_ENV' is not recognized as an internal or external command

npm install -g win-node-env
This will solve problem
if not for windows use below commands
set NODE_ENV=something node filename.js

Example 2: nodemon : The term 'nodemon' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again. At line:1 char:1 + nodemon index

npm install -g nodemon --save

Example 3: 'nodemon' is not recognized as an internal or external command, operable program or batch file.

Run: $ npm install -g nodemon

Run: $ npm install --save-dev nodemon

Change package.json file as:

"scripts": {
    "serve": "nodemon index.js"
}
Run: $ npm run serve