javascript - Error trying to install grunt -

i installed grunt using code:

npm install -g grunt-cli 

when run grunt --version returns me version:

grunt-cli v0.1.13 

but when go project's folder , run npm install, returns me errors messages:

npm err! install couldn't read dependencies npm err! package.json enoent, open '/applications/xampp/xamppfiles/htdocs/grunt/package.json' npm err! package.json not problem npm itself. npm err! package.json npm can't find package.json file in current directory.  npm err! system darwin 11.4.2 npm err! command "node" "/usr/local/bin/npm" "install" npm err! cwd /applications/xampp/xamppfiles/htdocs/grunt npm err! node -v v0.10.26 npm err! npm -v 1.4.3 npm err! path /applications/xampp/xamppfiles/htdocs/grunt/package.json npm err! code enopackagejson npm err! errno 34 npm err!  npm err! additional logging details can found in: npm err!     /applications/xampp/xamppfiles/htdocs/grunt/npm-debug.log npm err! not ok code 0 

what i'm doing wrong? google while , couldn't find answer question, can me?

npm install reads , installs dependencies package.json file , has nothing grunt.

node telling you don't have package.json file.

create package.json running npm init , stepping through process.

to save dependencies package.json file, run

npm install grunt --save-dev

where grunt in above command example of dependency.

also, haven't installed grunt - you've installed grunt command line interface job act interface local grunt installation. haven't installed grunt locally yet (from you've shown).

npm install grunt --save-dev install locally (and save dependency in package.json file)