tsconfig.json

{
    "compilerOptions": {
        /* Visit https://aka.ms/tsconfig to read more about this file */

        /* Language and Environment */
        // We can run on the latest browser so include the latest standards in output,
        // although it could still break if the browser didn't implement a specific feature from this standard
        "target": "ESNext" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
        "module": "ESNext" /* Specify what module code is generated. */,

        /* Modules */
        "rootDirs": [
            /* Specify the root folder within your source files. */
            "src",
            "tests"
        ],

        "lib": [
            // Default for ESNext target above except we exclude scripthost for windows native systems
            // https://github.com/microsoft/TypeScript/blob/main/src/lib/esnext.full.d.ts
            "DOM",
            "DOM.Iterable",
            "DOM.AsyncIterable",
            "ESNext",
            "WebWorker.ImportScripts",
            // Additional libs that should be supported by latest browsers separate from ESNext
            "ESNext.Array",
            "ESNext.AsyncIterable",
            "ESNext.Symbol",
            "ESNext.BigInt"
        ],

        // allow path aliases
        "baseUrl": ".",
        "paths": {
            "@App/*": ["src/*"],
            "@Mapping/*": ["src/lang/mappings/*"]
        },

        // import json directly into output
        "resolveJsonModule": true,

        // we are bundling the project js into single file for optimized loading
        "moduleResolution": "Bundler" /* Specify how TypeScript looks up a file from a given module specifier. */,
        // we use esbuild so disable duplicate JS output
        "noEmit": true /* Disable emitting files from a compilation. */,

        // strictness
        "noImplicitAny": true,
        "allowJs": false,

        /* Interop Constraints */
        "isolatedModules": true /* Ensure that each file can be safely transpiled without relying on other imports. */,
        "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
        "esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */,
        "forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,

        /* Type Checking */
        "strict": true /* Enable all strict type-checking options. */,
        "strictNullChecks": true /* When type checking, take into account 'null' and 'undefined'. */,
        "strictFunctionTypes": true /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */,
        "strictBindCallApply": true /* Check that the arguments for 'bind', 'call', and 'apply' methods match the original function. */,
        "strictPropertyInitialization": true /* Check for class properties that are declared but not set in the constructor. */,
        "noImplicitThis": true /* Enable error reporting when 'this' is given the type 'any'. */,
        "useUnknownInCatchVariables": true /* Default catch clause variables as 'unknown' instead of 'any'. */,
        "alwaysStrict": true /* Ensure 'use strict' is always emitted. */,

        // allow unused vars for this project, because its more prototyping
        //"noUnusedLocals": true,                           /* Enable error reporting when local variables aren't read. */
        //"noUnusedParameters": true,                       /* Raise an error when a function parameter isn't read. */
        "exactOptionalPropertyTypes": true /* Interpret optional property types as written, rather than adding 'undefined'. */,
        "noImplicitReturns": true /* Enable error reporting for codepaths that do not explicitly return in a function. */,
        "noFallthroughCasesInSwitch": true /* Enable error reporting for fallthrough cases in switch statements. */,

        // this would require index checks for many well-known properties like os.ENV - here it feels too strict than to allow runtime errors
        //"noUncheckedIndexedAccess": true,                 /* Add 'undefined' to a type when accessed using an index. */
        "noImplicitOverride": true /* Ensure overriding members in derived classes are marked with an override modifier. */,
        "noPropertyAccessFromIndexSignature": true /* Enforces using indexed accessors for keys declared using an indexed type. */,
        //"allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */
        //"allowUnreachableCode": true,                     /* Disable error reporting for unreachable code. */

        /* Completeness */
        "skipLibCheck": true /* Skip type checking all .d.ts files. */,
        "skipDefaultLibCheck": true
    }
}