[Node.js]解決npm install 時出現 gyp verb which failed Error: not found: python2 錯誤
===
###### tags: `Node.js` `前端` `nvm` `npm`

今天有新人來詢問為什麼公司Angular教育訓練課程裡的範例程式，照著教學做卻出現ERR。

看了一下原因，範例專案是多年前建立的，而新人電腦內的Node.js版本很新，和範例專案內的node-sass不匹配造成。

錯誤訊息如下
---

Fnpm ERR! code 1
npm ERR! path D:\Study-Folder\angular-zero\node_modules\node-sass
npm ERR! command failed
npm ERR! command C:\WINDOWS\system32\cmd.exe /d /s /c node scripts/build.js
npm ERR! Building: C:\Program Files\nodejs\node.exe D:\Study-Folder\angular-zero\node_modules\node-gyp\bin\node-gyp.js rebuild --verbose --libsass_ext= --libsass_cflags= --libsass_ldflags= --libsass_library=
npm ERR! gyp info it worked if it ends with ok
npm ERR! gyp verb cli [
npm ERR! gyp verb cli   'C:\\Program Files\\nodejs\\node.exe',
npm ERR! gyp verb cli   'D:\\Study-Folder\\angular-zero\\node_modules\\node-gyp\\bin\\node-gyp.js',
npm ERR! gyp verb cli   'rebuild',
npm ERR! gyp verb cli   '--verbose',
npm ERR! gyp verb cli   '--libsass_ext=',
npm ERR! gyp verb cli   '--libsass_cflags=',
npm ERR! gyp verb cli   '--libsass_ldflags=',
npm ERR! gyp verb cli   '--libsass_library='
npm ERR! gyp verb cli ]
npm ERR! gyp info using node-gyp@3.6.2
npm ERR! gyp info using node@16.13.2 | win32 | x64
npm ERR! gyp verb command rebuild []
npm ERR! gyp verb command clean []
npm ERR! gyp verb clean removing "build" directory
npm ERR! gyp verb command configure []
npm ERR! gyp verb check python checking for Python executable "python2" in the PATH
npm ERR! gyp verb `which` failed Error: not found: python2
npm ERR! gyp verb `which` failed     at getNotFoundError (D:\Study-Folder\angular-zero\node_modules\which\which.js:13:12)
npm ERR! gyp verb `which` failed     at F (D:\Study-Folder\angular-zero\node_modules\which\which.js:68:19)
npm ERR! gyp verb `which` failed     at E (D:\Study-Folder\angular-zero\node_modules\which\which.js:80:29)
npm ERR! gyp verb `which` failed     at D:\Study-Folder\angular-zero\node_modules\which\which.js:89:16
npm ERR! gyp verb `which` failed     at D:\Study-Folder\angular-zero\node_modules\isexe\index.js:42:5
npm ERR! gyp verb `which` failed     at D:\Study-Folder\angular-zero\node_modules\isexe\windows.js:36:5
npm ERR! gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:198:21)
npm ERR! gyp verb `which` failed  python2 Error: not found: python2
npm ERR! gyp verb `which` failed     at getNotFoundError (D:\Study-Folder\angular-zero\node_modules\which\which.js:13:12)
npm ERR! gyp verb `which` failed     at F (D:\Study-Folder\angular-zero\node_modules\which\which.js:68:19)
npm ERR! gyp verb `which` failed     at E (D:\Study-Folder\angular-zero\node_modules\which\which.js:80:29)
npm ERR! gyp verb `which` failed     at D:\Study-Folder\angular-zero\node_modules\which\which.js:89:16
npm ERR! gyp verb `which` failed     at D:\Study-Folder\angular-zero\node_modules\isexe\index.js:42:5
npm ERR! gyp verb `which` failed     at D:\Study-Folder\angular-zero\node_modules\isexe\windows.js:36:5
npm ERR! gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:198:21) {
npm ERR! gyp verb `which` failed   code: 'ENOENT'
npm ERR! gyp verb `which` failed }
npm ERR! gyp verb check python checking for Python executable "python" in the PATH
npm ERR! gyp verb `which` succeeded python C:\Users\2205001\AppData\Local\Programs\Python\Python39\python.EXE
npm ERR! gyp verb could not find "C:\Users\2205011\AppData\Local\Programs\Python\Python39\python.EXE". checking python launcher
npm ERR! gyp verb could not find "C:\Users\2205011\AppData\Local\Programs\Python\Python39\python.EXE". guessing location
npm ERR! gyp verb ensuring that file exists: C:\Python27\python.exe
npm ERR! gyp ERR! configure error
npm ERR! gyp ERR! stack Error: Can't find Python executable "C:\Users\2205011\AppData\Local\Programs\Python\Python39\python.EXE", you can set the PYTHON env variable.
npm ERR! gyp ERR! stack     at PythonFinder.<anonymous> (D:\Study-Folder\angular-zero\node_modules\node-gyp\lib\configure.js:508:16)
npm ERR! gyp ERR! stack     at D:\Study-Folder\angular-zero\node_modules\graceful-fs\polyfills.js:284:29
npm ERR! gyp ERR! stack     at FSReqCallback.oncomplete (node:fs:198:21)
npm ERR! gyp ERR! System Windows_NT 10.0.19044
sass_library="
npm ERR! gyp ERR! cwd D:\Study-Folder\angular-zero\node_modules\node-sass
npm ERR! gyp ERR! node -v v16.13.2
npm ERR! gyp ERR! node-gyp -v v3.6.2
npm ERR! gyp ERR! not ok
npm ERR! Build failed with error code: 1

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\2205011\AppData\Local\npm-cache\_logs\2022-06-21T02_01_44_054Z-debug.log

* 新人電腦安裝的Node.js版本是`v16.13.2`
* 範例專案`package-lock.json` 內 node-sass 版本為 `4.7.2`

由 https://www.npmjs.com/package/node-sass 可以查到匹配的版本，再不改動範例專案的情況下，就要將Node.js降到`v8`版本

但是因為同仁專案需求要使用`v16.13.2`，**不能直接降板RRR** ➡️ 那就要使用nvm來管理Node.js的版本!!

## 安裝 NVM 環境

:::info
簡介：
NVM 為 Node Version Manager 的縮寫，顧名思義就是「Node 版本管理控制」。

【常用的功能包含】：
1. 切換 Node.js 的版本
1. 使用特定 Node.js 作為預設啟用環境
1. 安裝不同的套件至特定的版本上
:::

官方gitHub
https://github.com/nvm-sh/nvm

Windosw 安裝懶人包：https://github.com/coreybutler/nvm-windows/releases

下載`nvm-setup.exe`去安裝即可

然後在 ==命列提示字元(以系統管理員身分執行)== 打上`nvm`指令，有看到以下畫面就是成功安裝了

:::danger
注意：一定要以系統管理員身分執行，沒有最高權限，或是用 VS code 內整合的 PowerShell 就會出現下面錯誤
:::


🔥 常用的 NVM 指令

* nvm install {{版本}}：安裝特定版本的 Node.js
* nvm uninstall {{版本}} ：刪除指定版本Node.js
* nvm ls：列出本定端所安裝的 Node.js 環境
* nvm use {{版本}}：當前命令列套用特定版本的 Node.js

1. 這邊直接於CDM輸入 `nvm install 8.11.3`，下載完畢後輸入 `nvm ls`可以看到目前本機內安裝的Node.js版本有`16.13.2`(使用中)和`8.11.3`

1. CDM輸入 `nvm use 8.11.3` 選擇使用v8.11.3的版本


最後再回到範例專案的資料夾，輸入指令`npm install`就安裝成功，可以再用`npm start`啟動範例專案囉~~~