Not able to use npm after installing yarn

Question

I installed yarn and now npm is not working. Whenever I try to use npm for number-is-nan, I get the following error:

Error: Cannot find module 'number-is-nan'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/usr/local/lib/node_modules/npm/node_modules/npmlog/node_modules/gauge/node_modules/string-width/node_modules/code-point-at/index.js:2:19)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)

Answer 1

Seems like installing yarn affected some files on npm. Try re-installing npm:

yarn global add npm

Answer 2

 "The easiest way to get started is to run npm install -g yarn". But if you go to the "install yarn" page in their docs, "npm install yarn" isn't listed on any of the platform-specific installation pages, and it's only offered as the third of three options on the "Alternatives" page. Furthermore when you npm install yarn it prints a deprecation warning, "It is recommended to install Yarn using the native installation method for your environment." So my question is if npm install is the easiest installation method, why isn't it a recommended method in their docs? Are there disadvantages to installing yarn using npm

Comments

Yes @rk

npm install -g yarn

is easy and most of the people use it. I have been using it for some time now and I don't find any problem or disadvantage. I had the same doubt and was researching this issue. After some time, I got few points on why using platform-specific installation packages is suggested over npm.

• npm does not give proper signature verification
• When you install applications using npm, suppose after some time you find a better package manager, it is tedious to make the transaction from npm
• upgrading to releases with platform-specific installation packages is easier