Example of pre and post scripts in package.json

package.json

{
  "name": "npm-scripts-example",
  "version": "1.0.0",
  "description": "npm scripts example",
  "scripts": {
    "prebuild": "echo I run before the build script",
    "build": "cross-env NODE_ENV=production webpack",
    "postbuild": "echo I run after the build script"
  }
}