tsconfig.json

React¹⁷.0.2, Typescript⁴.1.2, Created at July 21, 2021, Read Series…

The tsconfig.json file specifies the root files and the compiler options required to compile the project. A few key features are explained in this section.

{
  "compilerOptions": {
    "target": "es5",
    "lib": [
      "es6",
      ...
    ],
    "baseUrl": ".",
    ...    
  },
  "exclude": [
    "node_modules",
    "build",
    "**/*.spec.ts",
    ...
  ],
  "include": [
    "src",
    "src/**/*"
  ]
}

compilerOptions/target:es5 and compilerOptions/lib:[es6]

[Try to understand] target/es5: ECMAScript 2009. Use es5 as build target to support new more browsers and versions. You can change to es6 if you don’t want support lower version browsers.
[Try to understand] lib/es6: ECMAScript 2015 or es2015. Use es6 as lib to utilize more JavaScript packages and built-in features.

|   |Chrome   |IE     |Edge     |Firefox  |Safari   |Opera    |
+===+=========+=======+=========+=========+=========+=========+
|ES5|All      |IE 9.0 |All      |All      |All      |All      |
+---+---------+-------+---------+---------+---------+---------+
|ES6|v58/2017 |No     |v14/2016 |v54/2017 |v10/2016 |v55/2018 |

compilerOptions/baseUrl

[Try to understand] compilerOptions/baseUrl option is helping shorten deep path of Node.js modules.
[Try to understand] The tsconfig.json folder will be the root folder if baseUrl set to ‘.’.

// in index.tsx
import theme from './theme'; 
// is equivalent to:
import theme from 'src/theme';

In most of the cases, we can have src/somefolder/somemodel.ts

// e.g. src/somefolder/somemodel.ts, referenced in src/a/b/c/d.ts
import somemodelname from '../../../somefolder/somemodel'; 
// is equivalent to:
import somemodelname from 'src/somefolder/somemodel';

exclude/include

[Try to understand] include will include folders/files in compilation process.
[Try to understand] exclude will exclude folders/files in compilation process.
You can use:
— fixed path/filename: e.g. node_modules
— * matches zero or more characters (excluding directory separators)
-? matches any one character (excluding directory separators)
-**/ recursively matches any subdirectory

Github commits is here: Basic-1.1.1. tsconfig.json