Run npm start hint under Mac OS X 10.11.3: npmrr! Darwin 15.3.0

  node.js, question

Run npm start
Prompt error:

npm ERR!  Darwin 15.3.0
 npm ERR!  argv "/usr/local/bin/node" "/usr/local/bin/npm" "start"
 npm ERR!  node v5.7.1
 npm ERR!  npm  v3.6.0
 npm ERR!  missing script: start
 npm ERR!
 npm ERR!  If you need help, you may report this error at:
 npm ERR!  < >
 npm ERR!  Please include the following file with any support request:
 npm ERR!  /Users/ username /snapterest/npm-debug.log

npm run startOr ..npm run-script start
And you need to define start as a field command in scripts of package.json