由于业务需要，需要在系统中使用文件系统，安装fs-extra时出现以下问题
问题1.
BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.
If you want to include a polyfill, you need to:
- add a fallback 'resolve.fallback: { "path": require.resolve("path-browserify") }'
- install 'path-browserify'
If you don't want to include a polyfill, you can use an empty module like this:
resolve.fallback: { "path": false }
问题2.
BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.
If you want to include a polyfill, you need to:
- add a fallback 'resolve.fallback: { "constants": require.resolve("constants-browserify") }'
- install 'constants-browserify'
If you don't want to include a polyfill, you can use an empty module like this:
resolve.fallback: { "constants": false }
问题3.
BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.
If you want to include a polyfill, you need to:
- add a fallback 'resolve.fallback: { "stream": require.resolve("stream-browserify") }'
- install 'stream-browserify'
If you don't want to include a polyfill, you can use an empty module like this:
resolve.fallback: { "stream": false }
多方寻找解决方法后，使用以下方法得以解决。
1. 安装path-browserify 和 constants-browserify
npm i path-browserify --save
npm i constants-browserify --save
npm i stream-browserify --save
2. 在tsconfig.json中的compilerOptions下，增加以下内容
"paths": {
"stream": [ "./node_modules/stream-browserify" ],
"path": [ "./node_modules/path-browserify" ],
"constants": ["./node_modules/constants-browserify"]
},
3.在angular.json中projects->项目名->architect->build->options下增加
"allowedCommonJsDependencies": [
"stream","path", "constants"
],
这样以上问题不出现了，但还有其他问题，问题如下：
./node_modules/graceful-fs/graceful-fs.js:1:9-22 - Error: Module not found: Error: Can't resolve 'fs' in
./node_modules/jsonfile/index.js:8:8-21 - Error: Module not found: Error: Can't resolve 'fs' in
解决方法：
在package.json的根部中增加以下内容：
"browser": {
"fs": false
}
