npm install -g failing, getting npm ERR! code EACCES - node.js

Question

When I run npm install -g typescript the following message shows:
npm ERR! code EACCES
npm ERR! syscall mkdir
npm ERR! path /usr/local/lib/node_modules/typescript
npm ERR! errno -13
npm ERR! Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/typescript'
npm ERR! [Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/typescript'] {
npm ERR! errno: -13,
npm ERR! code: 'EACCES',
npm ERR! syscall: 'mkdir',
npm ERR! path: '/usr/local/lib/node_modules/typescript'
npm ERR! }
npm ERR!
npm ERR! The operation was rejected by your operating system.
npm ERR! It is likely you do not have the permissions to access this file as the current user
npm ERR!
npm ERR! If you believe this might be a permissions issue, please double-check the
npm ERR! permissions of the file and its containing directories, or try running
npm ERR! the command again as root/Administrator.
npm ERR! A complete log of this run can be found in:
npm ERR! /Users/alexz/.npm/_logs/2021-12-26T10_45_08_412Z-debug.log
I tried to check if I have successfully installed TypeScript, if I run npm ls typescript it shows:
alexz# /Users/alexz
└── typescript#4.5.4
I am confused if I have installed TypeScript or not, because if I do tsc -v it tells me the tsc command is not found. How do I fix the above problem? Thanks!

Answer 1

It is a permission issue. You could read Resolving EACCES permissions errors when installing packages globally to change npm's permissions or you could use sudo command as below.
It may ask you your computer password.
sudo npm install -g typescript