How to run ESLint in you travis CI

.travis.yml

language: node_js
node_js:
  - "6"

script:
  - npm run lint
  - npm run build
  - npm test

package.json

{
 ...
 "scripts": {
  "lint": "./node_modules/.bin/eslint **/*.js",
  "build": "...",
  "test": "..."
 }
 ...
}