cnpm install rimraf -g package.json 可以像下面这样配置， 这样 每次build时候 都会把原来build好的 全部删除  重新编译

{  "name": "webpack-ensure",  "version": "1.0.0",  "description": "",  "main": "index.js",  "scripts": {    "test": "echo \"Error: no test specified\" && exit 1",    "build": "rimraf dist && webpack"  },  "author": "",  "license": "ISC",  "devDependencies": {    "html-webpack-plugin": "^2.25.0",    "webpack": "^1.14.0"  }}