TYPESCRIPT_CONFIG.md

TypeScript Configuration

This document explains the fields set in the tsconfig.json file.

"compilerOptions"

Language and Environment

• "target": Set the JavaScript language version for emitted JavaScript and include compatible library declarations.
• "experimentalDecorators: Enable experimental support for TC39 stage 2 draft decorators. Refer to reflect-metadata here for details.
• "emitDecoratorMetadata: Emit design-type metadata for decorated declarations in source files.

Modules

• "module": Specify what module code is generated.

Emit

• "sourceMap": Create source map files for emitted JavaScript files.
• "outDir": Specify an output folder for all emitted files.
• "removeComments": Disable emitting comments.
• "noEmitOnError": Disable emitting files if any type checking errors are reported.

Interop Constraints

• "esModuleInterop": Emit additional JavaScript to ease support for importing CommonJS modules. This enables allowSyntheticDefaultImports for type compatibility. This option could be removed when "module is set to ES Module.
• "forceConsistentCasingInFileName": Ensure that casing is correct in imports.

Type Checking

• "strict": Enable all strict type checking options.
• "noUnusedLocals: Enable error reporting when a local variable isn't read.
• "noUnusedParameters": Raise an error when a function parameter isn't read.
• "noFallthroughCasesInSwitch": Enable error reporting for fallthrough cases in switch statements.
• "noImplicitOverride": Ensure overriding members in derived classes are marked with an override modifier.
• "allowUnusedLabels": Disable error reporting for unused labels.
• "allowUnreachableCode": Disable error reporting for unreachable code.

Completeness

• "skipLibCheck": Skip type checking all .d.ts files. This is set to true by default.

Others

• "include": Specifies a list of glob patterns that match files to be included in compilation.