运行nodejs项目，npm start启动项目import报错，SyntaxError: Cannot use import statement outside a module

比眉伴天荒 2023-06-17 13:55 7阅读 0赞

运行nodejs项目报错如下：

$ npm start                                                                                                                                                                  
                                                                                                                                                                                 
    > m-mall-admin@1.0.0 start D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin                                                                        
    > babel-node ./bin/www                                                                                                                                                       
                                                                                                                                                                                 
    (node:4488) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.                                                               
    D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin\bin\www:4                                                                                         
    import app from '../app';                                                                                                                                                    
    ^^^^^^                                                                                                                                                                       
                                                                                                                                                                                 
    SyntaxError: Cannot use import statement outside a module                                                                                                                    
        at wrapSafe (internal/modules/cjs/loader.js:1043:16)                                                                                                                     
        at Module._compile (internal/modules/cjs/loader.js:1091:27)                                                                                                              
        at loader (D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin\node_modules\babel-register\lib\node.js:146:5)                                     
        at Object.require.extensions.<computed> [as .js] (D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin\node_modules\babel-register\lib\node.js:156:
    7)                                                                                                                                                                           
        at Module.load (internal/modules/cjs/loader.js:976:32)                                                                                                                   
        at Function.Module._load (internal/modules/cjs/loader.js:884:14)                                                                                                         
        at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:67:12)                                                                                      
        at D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin\node_modules\babel-cli\lib\_babel-node.js:151:24                                           
        at Object.<anonymous> (D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin\node_modules\babel-cli\lib\_babel-node.js:152:7)                       
        at Module._compile (internal/modules/cjs/loader.js:1121:30)                                                                                                              
    npm ERR! code ELIFECYCLE                                                                                                                                                     
    npm ERR! errno 1                                                                                                                                                             
    npm ERR! m-mall-admin@1.0.0 start: `babel-node ./bin/www`                                                                                                                    
    npm ERR! Exit status 1                                                                                                                                                       
    npm ERR!                                                                                                                                                                     
    npm ERR! Failed at the m-mall-admin@1.0.0 start 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\lenovo\AppData\Roaming\npm-cache\_logs\2019-11-29T03_31_13_816Z-debug.log                                                                              
                                                                                                                                                                                 
    D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin (master -> origin) (m-mall-admin@1.0.0)                                                           
    $ node -v                                                                                                                                                                    
    v13.2.0                                                                                                                                                                      
                                                                                                                                                                                 
    D:\SoftwareAndProgram\program\weixin\miniprogram\mini-mall\mini-mall-admin (master -> origin) (m-mall-admin@1.0.0)                                                           
    $ npm -v                                                                                                                                                                     
    6.13.1

大概意思是nodejs不支持import语法，如果要支持，需要babel来支持。

## babel的安装 ##

所以我们来安装babel吧， 有了babel， 能够使用更多高级词法！

在项目根目录下，执行：

npm install --save babel-core
    npm install --save babel-preset-env 或者 npm install --save babel-preset-es2015
    npm install babel-cli -g

接着在`项目根目录下`创建一个名字为`.babelrc`的文件， 文件内容入如下（ 要注意window系统下创建这种文件系统会提示你：“必须键入文件名” ， 你可以找别的方式去创建， 我是在开发工具的工程目录中把这个文件创建出来的，也可以用`cmder神器的vim命令`）：

{ 
        "presets": [
          "es2015"
        ],
        "plugins": []
    }

或者：

{                 
        "presets": [ 
             "env"   
         ],          
        "plugins": []
    }

到目前为止babel算是安装完毕了。

接下来可以用`npm start`和`babel-node app.js`运行项目。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWFiaW8uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]

## 参考 ##

[用babel解决nodejs项目import报错，nodejs之使用babel支持es6和pm2下使用babel][babel_nodejs_import_nodejs_babel_es6_pm2_babel]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWFiaW8uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191129225747635.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9saWFiaW8uYmxvZy5jc2RuLm5ldA==,size_16,color_FFFFFF,t_70
[babel_nodejs_import_nodejs_babel_es6_pm2_babel]: https://blog.csdn.net/wushichao0325/article/details/85262063