Why babel alias did not work when set up was all correct?

Question

1.I'm building a react project and try to use Babel to simplified the import. Here is the code for babel.config.js file.

module.exports = {
    presets: ['module:metro-react-native-babel-preset'],
    plugins: [
      [
        'module-resolver',
        {
          alias: {
            "pages": "./src/Page",
          },
        },
      ],
    ],
  };

This is the code for jsonconfig,json file

{
    "compilerOptions": {
        "baseUrl": ".",
        "paths": {
            "pages/*": [
                "./src/Page/*"
            ]
        }
    }
}

Then I try to import the Login component from pages module in App.js file

import React, { useState, useEffect } from "react";
import ReactDOM from 'react-dom';
import "./Boostrap/bootstrap5.css";
import "./Boostrap/style-main.css";
import axios from "axios";
// import Login from "./Page/Login";

import Login from "pages/Login";

But I got this error \frontend\node_modules\pages doesn't exist @ ./src/index.js 7:0-24 12:38-41 ERROR in ./src/App.js 12:0-32

Module not found: Error: Can't resolve 'pages/Login' in 'C:\Users\jason\Desktop\demoApp\frontend\src'`

: The folder structure would be like :

These are another error message

ERROR in ./src/App.js 11:0-32
Module not found: Error: Can't resolve 'pages/Login' in 'C:\Users\jason\Desktop\demoApp\frontend\src'
resolve 'pages/Login' in 'C:\Users\jason\Desktop\demoApp\frontend\src'
  Parsed request is a module
  using description file: C:\Users\jason\Desktop\demoApp\frontend\package.json (relative path: ./src)
    Field 'browser' doesn't contain a valid alias configuration
    resolve as module
      C:\Users\jason\Desktop\demoApp\frontend\src\node_modules doesn't exist or is not a directory
      looking for modules in C:\Users\jason\Desktop\demoApp\frontend\node_modules
        C:\Users\jason\Desktop\demoApp\frontend\node_modules\pages doesn't exist
      C:\Users\jason\Desktop\demoApp\node_modules doesn't exist or is not a directory     
      C:\Users\jason\Desktop\node_modules doesn't exist or is not a directory
      C:\Users\jason\node_modules doesn't exist or is not a directory
      C:\Users\node_modules doesn't exist or is not a directory
      C:\node_modules doesn't exist or is not a directory
      looking for modules in C:\Users\jason\Desktop\demoApp\frontend\node_modules
        C:\Users\jason\Desktop\demoApp\frontend\node_modules\pages doesn't exist
 @ ./src/index.js 7:0-24 12:38-41

The folder structure: So the Page folder structure would be like

├───Component
│   ├───AddPopUp
│   ├───Buttons
│   ├───FacilityForms
│   ├───Filters
│   ├───Footers
│   ├───InputTexts
│   ├───InspectionFilter
│   ├───Labels
│   ├───Navigation
│   ├───NavTab
│   ├───PageHeading
│   ├───SearchBox
│   ├───Table
│   └───TableRow
└───Page
    ├───ClientManagement
    └───ClientSetting` ``

Answer 1

Specify the root path in your Babel config. For .js Babel config files, we need to use require.resolve('babel-plugin-module-resolver') instead of module-resolver.

module.exports = {
    presets: ['module:metro-react-native-babel-preset'],
    plugins: [
      [
        require.resolve('babel-plugin-module-resolver'),
        {
          root: ['./src/'],
          alias: {
            "pages": "./src/Page", // This works for me in my project
            // "pages": "./Page", // This is as per documentation
          },
        },
      ],
    ],
  };

Answer 2

in "react-native": "0.68.1" it worked after replce babel.config.js by .babelrc

my .babelrc is

{
  "presets": ["module:metro-react-native-babel-preset"],
  "plugins": [
    [
      "module-resolver",
      {
        "extensions": [".ios.js", ".android.js", ".js", ".ts", ".tsx", ".json"],
        "root": ["."],
        "alias": {
          "@components": "./src/components"
        }
      }
    ]
  ]
}

and my tsconfig.json

{
  "compilerOptions": {
    /* Basic Options */
    "target": "esnext" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
    "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
    "lib": [
      "es2017"
    ] /* Specify library files to be included in the compilation. */,
    "allowJs": true /* Allow javascript files to be compiled. */,
    // "checkJs": true,                       /* Report errors in .js files. */
    "jsx": "react-native" /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */,
    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    // "outDir": "./",                        /* Redirect output structure to the directory. */
    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    // "removeComments": true,                /* Do not emit comments to output. */
    "noEmit": true /* Do not emit outputs. */,
    // "incremental": true,                   /* Enable incremental compilation */
    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
    "isolatedModules": true /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */,

    /* Strict Type-Checking Options */
    "strict": true /* Enable all strict type-checking options. */,
    "noImplicitAny": true /* Raise error on expressions and declarations with an implied 'any' type. */,
    "strictNullChecks": true /* Enable strict null checks. */,
    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */

    /* Additional Checks */
    // "noUnusedLocals": true,                /* Report errors on unused locals. */
    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */

    /* Module Resolution Options */
    "moduleResolution": "node" /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */,
    "baseUrl": "." /* Base directory to resolve non-absolute module names. */,

    "paths": {
      "@components/*": ["./src/components/*"],
    } /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */,
    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    // "types": [],                           /* Type declaration files to be included in compilation. */
    "allowSyntheticDefaultImports": true /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */,
    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
    "skipLibCheck": true /* Skip type checking of declaration files. */,
    "resolveJsonModule": true /* Allows importing modules with a ‘.json’ extension, which is a common practice in node projects. */

    /* Source Map Options */
    // "sourceRoot": "./",                    /* Specify the location where debugger should locate TypeScript files instead of source locations. */
    // "mapRoot": "./",                       /* Specify the location where debugger should locate map files instead of generated locations. */
    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */

    /* Experimental Options */
    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
  },
  "include": ["src", "*.config.js"],
  "exclude": [
    "node_modules",
    "babel.config.js",
    "metro.config.js",
    "jest.config.js"
  ]
}