dirname is not defined

ReferenceError: _dirname is not defined

    at Object.<anonymous> (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\webpack.config.js:5:22)

    at Module._compile (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\v8-compile-cache\v8-compile-cache.js:178:30)

    at Object.Module._extensions..js (module.js:654:10)

    at Module.load (module.js:556:32)

    at tryModuleLoad (module.js:499:12)

    at Function.Module._load (module.js:491:3)

    at Module.require (module.js:587:17)

    at require (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\v8-compile-cache\v8-compile-cache.js:159:20)

    at WEBPACK_OPTIONS (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack-cli\bin\convert-argv.js:133:13)

    at requireConfig (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack-cli\bin\convert-argv.js:135:6)

    at C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack-cli\bin\convert-argv.js:142:17

    at Array.forEach (<anonymous>)

    at module.exports (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack-cli\bin\convert-argv.js:140:15)

    at yargs.parse (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack-cli\bin\webpack.js:240:39)

    at Object.parse (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\yargs\yargs.js:552:18)

    at C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack-cli\bin\webpack.js:218:8

    at Object.<anonymous> (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack-cli\bin\webpack.js:515:3)

    at Module._compile (module.js:643:30)

    at Object.Module._extensions..js (module.js:654:10)

    at Module.load (module.js:556:32)

    at tryModuleLoad (module.js:499:12)

    at Function.Module._load (module.js:491:3)

    at Module.require (module.js:587:17)

    at require (internal/module.js:11:18)

    at Object.<anonymous> (C:\Users\lianghuiling\Desktop\Intelligent school campus\newitem\node_modules\webpack\bin\webpack.js:80:2)

    at Module._compile (module.js:643:30)

    at Object.Module._extensions..js (module.js:654:10)

    at Module.load (module.js:556:32)

    at tryModuleLoad (module.js:499:12)

    at Function.Module._load (module.js:491:3)

npm ERR! code ELIFECYCLE

npm ERR! errno 1

npm ERR! newitem@1.0.0 build: `webpack --config webpack.config.js`

npm ERR! Exit status 1

npm ERR!

npm ERR! Failed at the newitem@1.0.0 build script.

npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:

npm ERR!     C:\Users\lianghuiling\AppData\Roaming\npm-cache\_logs\2018-05-24T14_29_22_106Z-debug.log