Execution process of NPM run XX

npm run xx The implementation process of

npm run xxx This xxx Is in package.json Configured in .
package.json Medium scripts Medium key by xxx,value For actual commands .

npm run xxx When , I will go to the project first package.json Look for... In the file scripts Find the corresponding xxx, And then execute xxx The order of , For example, start vue project npm rum serve Actually npm run vue-cli-service serve --open

vue-cli 2.0

"script":{
    
  "dev": "webpack-dev-server --inline --progress --config build/webpack.dev.conf.js",
  "start": "npm run dev",
  "build": "node build/build.js"
}

vue-cli 3.0

"script":{
    
    "serve": "vue-cli-service serve --open",
    "build": "vue-cli-service build",
	"lint": "vue-cli-service lint"
}

Why not do it directly vue-cli-service serve But to execute npm run serve Well
Because there is no vue-cli-service Instructions , Direct execution will report an error .

** Why execute npm rum serve You can make it when you want to ?
**
When installing dependencies , Will be in node_modules/.bin/ Create several in the directory vue-cli-service Executable named ,bin The files in the directory represent soft connection .
Use npm run serve perform vue-cli-service serve when , Will arrive ./node_modules/.bin Find vue-cli-service. File as Script to execute , It is equivalent to the execution of ./node_modules/.bin/vue-cli-service serve（ final serve Pass in as a parameter ）

This bin Where did the soft link files in the directory come from ？ How does it know where this soft connection is executed ？
Source code in the Library package.json in , Can find bin Field , Used to create a soft link during installation to point to bin Address in .

npm i When ,npm Just help us configure this soft connection , In fact, this kind of soft connection is equivalent to a mapping , perform npm run xxx When , It will come to node_modules/bin Find the corresponding mapping file in , Then find the corresponding js File to execute .

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author ： Sunshine is sunny link ：https://juejin.cn/post/7078924628525056007 source ： Rare earth digs gold The copyright belongs to the author . Commercial reprint please contact the author for authorization , Non-commercial reprint please indicate the source .