Bonjour

voilà je suis entrain d'apprendre React, je suis bloqué dans une chose depuis deux jours

je crée une application avec create-react-app là tout va bien

j'utilise puis npm install --save react-router-dom

là j'ai ça

C:\Users\Ghanou\Desktop\frameworkJs\react-spa>npm install --save react-router-dom
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\jest.cmd as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\jest
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\jest as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\jest
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\uglifyjs.cmd as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\uglify-js
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\uglifyjs as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\uglify-js
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\html-minifier\node_modules\.bin\uglifyjs.cmd as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\html-minifier\node_modules\uglify-js
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\html-minifier\node_modules\.bin\uglifyjs as it wasn't
installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\html-minifier\node_modules\uglify-js
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\esparse.cmd as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\esprima
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\esvalidate.cmd as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\esprima
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\esparse as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\esprima
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\esvalidate as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\esprima
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\espree\node_modules\.bin\acorn.cmd as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\espree\node_modules\acorn
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\espree\node_modules\.bin\acorn as it wasn't installed
by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\espree\node_modules\acorn
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\browserslist.cmd as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\browserslist
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\.bin\browserslist as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\browserslist
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\autoprefixer\node_modules\.bin\browserslist.cmd as it
wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\autoprefixer\node_modules\browserslist
npm WARN rm not removing C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\autoprefixer\node_modules\.bin\browserslist as it wasn't installed by C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\autoprefixer\node_modules\browserslist
npm WARN react-router-dom@4.3.1 requires a peer of react@>=15 but none is installed. You must install peer dependencies yourself.
npm WARN react-router@4.3.1 requires a peer of react@>=15 but none is installed. You must install peer dependencies yourself.

npm ERR! path C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\jest\node_modules
npm ERR! code EPERM
npm ERR! errno -4048
npm ERR! syscall mkdir
npm ERR! Error: EPERM: operation not permitted, mkdir 'C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\jest\node_modules'
npm ERR!  { Error: EPERM: operation not permitted, mkdir 'C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\jest\node_modules'
npm ERR!   cause:
npm ERR!    { Error: EPERM: operation not permitted, mkdir 'C:\Users\Ghanou\Desktop\frameworkJs\react-spa\node_modules\jest\node_modules'
npm ERR!      errno: -4048,
npm ERR!      code: 'EPERM',
npm ERR!      syscall: 'mkdir',
npm ERR!      path: 'C:\\Users\\Ghanou\\Desktop\\frameworkJs\\react-spa\\node_modules\\jest\\node_modules' },
npm ERR!   stack: 'Error: EPERM: operation not permitted, mkdir \'C:\\Users\\Ghanou\\Desktop\\frameworkJs\\react-spa\\node_modules\\jest\\node_modules\'',
npm ERR!   errno: -4048,
npm ERR!   code: 'EPERM',
npm ERR!   syscall: 'mkdir',
npm ERR!   path: 'C:\\Users\\Ghanou\\Desktop\\frameworkJs\\react-spa\\node_modules\\jest\\node_modules',
npm ERR!   parent: 'react-spa' }
npm ERR!
npm ERR! Please try running this command again as root/Administrator.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\Ghanou\AppData\Roaming\npm-cache\_logs\2018-07-12T10_32_09_233Z-debug.log

quand je fait yarn pour démarrer l'application ça m'affiche ça :

yarn run v1.6.0
$ react-scripts start
'react-scripts' n’est pas reconnu en tant que commande interne
ou externe, un programme exécutable ou un fichier de commandes.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Merci pour vos réponse