Error: EACCES: permission denied, mkdir '/npm' when installing angular code example

Example 1: npm ERR! Error: EACCES: permission denied, symlink '../lib/node_modules/@angular/cli/bin/ng' -> '/usr/bin/ng'

sudo npm install -g @angular/cli
sudo chown -R $USER /usr/local/lib/node_modules

Example 2: Error: EACCES: permission denied, mkdir

add sudo , example sudo npm i nodemon -g