react 报错

npm run start 出现的问题

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ERROR in ./src/App.js 7:0-23 Module not found: Error: Can't resolve './polyfill.js' in 'E:\code\project2022\project220707\2022071601\demo\src'   ERROR in ../node_modules/cipher-base/index.js 3:16-43 Module not found: Error: Can't resolve 'stream' in 'E:\code\project2022\project220707\2022071601\node_modules\cipher-base'   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 }   ERROR in ../node_modules/eth-lib/lib/bytes.js 9:193-227 Module not found: Error: Can't resolve 'crypto' in 'E:\code\project2022\project220707\2022071601\node_modules\eth-lib\lib'   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: { "crypto": require.resolve("crypto-browserify") }'         - install 'crypto-browserify' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "crypto": false }   ERROR in ../node_modules/ethereumjs-util/dist.browser/account.js 39:31-48 Module not found: Error: Can't resolve 'assert' in 'E:\code\project2022\project220707\2022071601\node_modules\ethereumjs-util\dist.browser'   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: { "assert": require.resolve("assert/") }'         - install 'assert' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "assert": false }   ERROR in ../node_modules/ethereumjs-util/dist.browser/address.js 14:31-48 Module not found: Error: Can't resolve 'assert' in 'E:\code\project2022\project220707\2022071601\node_modules\ethereumjs-util\dist.browser'   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: { "assert": require.resolve("assert/") }'         - install 'assert' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "assert": false }   ERROR in ../node_modules/ethereumjs-util/dist.browser/object.js 14:31-48 Module not found: Error: Can't resolve 'assert' in 'E:\code\project2022\project220707\2022071601\node_modules\ethereumjs-util\dist.browser'   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: { "assert": require.resolve("assert/") }'         - install 'assert' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "assert": false }   ERROR in ../node_modules/web3-eth-accounts/lib/index.js 31:74-91 Module not found: Error: Can't resolve 'crypto' in 'E:\code\project2022\project220707\2022071601\node_modules\web3-eth-accounts\lib'   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: { "crypto": require.resolve("crypto-browserify") }'         - install 'crypto-browserify' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "crypto": false }   ERROR in ../node_modules/web3-eth-accounts/node_modules/eth-lib/lib/bytes.js 7:193-227 Module not found: Error: Can't resolve 'crypto' in 'E:\code\project2022\project220707\2022071601\node_modules\web3-eth-accounts\node_modules\eth-lib\lib'   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: { "crypto": require.resolve("crypto-browserify") }'         - install 'crypto-browserify' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "crypto": false }   ERROR in ../node_modules/web3-providers-http/lib/index.js 30:11-26 Module not found: Error: Can't resolve 'http' in 'E:\code\project2022\project220707\2022071601\node_modules\web3-providers-http\lib'   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: { "http": require.resolve("stream-http") }'         - install 'stream-http' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "http": false }   ERROR in ../node_modules/web3-providers-http/lib/index.js 32:12-28 Module not found: Error: Can't resolve 'https' in 'E:\code\project2022\project220707\2022071601\node_modules\web3-providers-http\lib'   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: { "https": require.resolve("https-browserify") }'         - install 'https-browserify' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "https": false }   ERROR in ../node_modules/web3-providers-ws/lib/helpers.js 11:12-26 Module not found: Error: Can't resolve 'url' in 'E:\code\project2022\project220707\2022071601\node_modules\web3-providers-ws\lib'   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: { "url": require.resolve("url/") }'         - install 'url' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "url": false }   ERROR in ../node_modules/xhr2-cookies/dist/xml-http-request.js 37:11-26 Module not found: Error: Can't resolve 'http' in 'E:\code\project2022\project220707\2022071601\node_modules\xhr2-cookies\dist'   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: { "http": require.resolve("stream-http") }'         - install 'stream-http' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "http": false }   ERROR in ../node_modules/xhr2-cookies/dist/xml-http-request.js 39:12-28 Module not found: Error: Can't resolve 'https' in 'E:\code\project2022\project220707\2022071601\node_modules\xhr2-cookies\dist'   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: { "https": require.resolve("https-browserify") }'         - install 'https-browserify' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "https": false }   ERROR in ../node_modules/xhr2-cookies/dist/xml-http-request.js 41:9-22 Module not found: Error: Can't resolve 'os' in 'E:\code\project2022\project220707\2022071601\node_modules\xhr2-cookies\dist'   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: { "os": require.resolve("os-browserify/browser") }'         - install 'os-browserify' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "os": false }   ERROR in ../node_modules/xhr2-cookies/dist/xml-http-request.js 43:10-24 Module not found: Error: Can't resolve 'url' in 'E:\code\project2022\project220707\2022071601\node_modules\xhr2-cookies\dist'   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: { "url": require.resolve("url/") }'         - install 'url' If you don't want to include a polyfill, you can use an empty module like this:         resolve.fallback: { "url": false }

　　

　　

解决方式

https://github.com/ChainSafe/web3.js#trouble-shooting-and-known-issues