npm : The term 'npm' 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 + npm install + ~~~ + CategoryInfo : ObjectNotFound: (npm:String) , CommandNotFoundException + FullyQualifiedErrorId : CommandNotFoundException
This error means that npm is not installed on your machine:
Quote from https://www.npmjs.com/get-npm :
npm is installed with Node.js
npm is distributed with Node.js – which means that when you download Node.js, you automatically get npm installed on your computer.
node.js download from https://nodejs.org/en/