Optional
allowArbitraryExtensions?: boolean | nullEnable importing files with any extension, provided a declaration file is present.
Optional
allowImportingTsExtensions?: boolean | nullAllow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set.
Optional
allowJs?: boolean | nullAllow JavaScript files to be a part of your program. Use the checkJS
option to get errors from these files.
Optional
allowSyntheticDefaultImports?: boolean | nullAllow 'import x from y' when a module doesn't have a default export.
Optional
allowUmdGlobalAccess?: boolean | nullAllow accessing UMD globals from modules.
Optional
allowUnreachableCode?: boolean | nullDisable error reporting for unreachable code.
Optional
allowUnusedLabels?: boolean | nullDisable error reporting for unused labels.
Optional
alwaysStrict?: boolean | nullEnsure 'use strict' is always emitted.
Optional
assumeChangesOnlyAffectDirectDependencies?: boolean | nullHave recompiles in '--incremental' and '--watch' assume that changes within a file will only affect files directly depending on it. Requires TypeScript version 3.8 or later.
Optional
baseUrl?: string | nullSpecify the base directory to resolve non-relative module names.
Optional
charset?: string | nullNo longer supported. In early versions, manually set the text encoding for reading files.
Optional
checkJs?: boolean | nullEnable error reporting in type-checked JavaScript files.
Optional
composite?: boolean | nullEnable constraints that allow a TypeScript project to be used with project references.
Optional
customConditions?: (string | null)[] | nullConditions to set in addition to the resolver-specific defaults when resolving imports.
Optional
declaration?: boolean | nullGenerate .d.ts files from TypeScript and JavaScript files in your project.
Optional
declarationDir?: string | nullSpecify the output directory for generated declaration files.
Optional
declarationMap?: boolean | nullCreate sourcemaps for d.ts files.
Optional
diagnostics?: boolean | nullOutput compiler performance information after building.
Optional
disableReferencedProjectLoad?: boolean | nullReduce the number of projects loaded automatically by TypeScript.
Optional
disableSizeLimit?: boolean | nullRemove the 20mb cap on total source code size for JavaScript files in the TypeScript language server.
Optional
disableSolutionSearching?: boolean | nullOpt a project out of multi-project reference checking when editing.
Optional
disableSourceOfProjectReferenceRedirect?: boolean | nullDisable preferring source files instead of declaration files when referencing composite projects
Optional
downlevelIteration?: boolean | nullEmit more compliant, but verbose and less performant JavaScript for iteration.
Optional
emitBOM?: boolean | nullEmit a UTF-8 Byte Order Mark (BOM) in the beginning of output files.
Optional
emitDeclarationOnly?: boolean | nullOnly output d.ts files and not JavaScript files.
Optional
emitDecoratorMetadata?: boolean | nullEmit design-type metadata for decorated declarations in source files.
Optional
erasableSyntaxOnly?: boolean | nullDo not allow runtime constructs that are not part of ECMAScript.
Optional
esModuleInterop?: boolean | nullEmit additional JavaScript to ease support for importing CommonJS modules. This enables allowSyntheticDefaultImports
for type compatibility.
Optional
exactOptionalPropertyTypes?: boolean | nullDifferentiate between undefined and not present when type checking
Optional
experimentalDecorators?: boolean | nullEnable experimental support for TC39 stage 2 draft decorators.
Optional
extendedDiagnostics?: boolean | nullOutput more detailed compiler performance information after building.
Optional
fallbackPolling?: Specify the polling strategy to use when the system runs out of or doesn't support native file watchers. Requires TypeScript version 3.8 or later.
Optional
forceConsistentCasingInFileNames?: boolean | nullEnsure that casing is correct in imports.
Optional
generateCpuProfile?: string | nullEmit a v8 CPU profile of the compiler run for debugging.
Optional
importHelpers?: boolean | nullAllow importing helper functions from tslib once per project, instead of including them per-file.
Optional
importsNotUsedAsValues?: "remove" | "preserve" | "error"Specify emit/checking behavior for imports that are only used for types.
Optional
incremental?: boolean | nullEnable incremental compilation. Requires TypeScript version 3.4 or later.
Optional
inlineSourceMap?: boolean | nullInclude sourcemap files inside the emitted JavaScript.
Optional
inlineSources?: boolean | nullInclude source code in the sourcemaps inside the emitted JavaScript.
Optional
isolatedDeclarations?: boolean | nullRequire sufficient annotation on exports so other tools can trivially generate declaration files.
Optional
isolatedModules?: boolean | nullEnsure that each file can be safely transpiled without relying on other imports.
Optional
jsx?: "preserve" | "react" | "react-jsx" | "react-jsxdev" | "react-native"Specify what JSX code is generated.
Optional
jsxFactory?: string | nullSpecify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'
Optional
jsxFragmentFactory?: string | nullSpecify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'.
Optional
jsxImportSource?: string | nullSpecify module specifier used to import the JSX factory functions when using jsx: react-jsx
.
Optional
keyofStringsOnly?: boolean | nullMake keyof only return strings instead of string, numbers or symbols. Legacy option.
Optional
lib?: Specify a set of bundled library declaration files that describe the target runtime environment.
Optional
libReplacement?: boolean | nullEnable lib replacement.
Optional
listEmittedFiles?: boolean | nullPrint the names of emitted files after a compilation.
Optional
listFiles?: boolean | nullPrint all of the files read during the compilation.
Optional
listFilesOnly?: boolean | nullPrint names of files that are part of the compilation and then stop processing.
Optional
mapRoot?: string | nullSpecify the location where debugger should locate map files instead of generated locations.
Optional
maxNodeModuleJsDepth?: number | nullSpecify the maximum folder depth used for checking JavaScript files from node_modules
. Only applicable with allowJs
.
Optional
module?: (Specify what module code is generated.
Optional
moduleDetection?: "auto" | "legacy" | "force"Specify how TypeScript determine a file as module.
Optional
moduleResolution?: (Specify how TypeScript looks up a file from a given module specifier.
Optional
newLine?: ("crlf" | "lf" | { [k: string]: unknown }) & (Set the newline character for emitting files.
Optional
noCheck?: boolean | nullDisable full type checking (only critical parse and emit errors will be reported)
Optional
noEmit?: boolean | nullDisable emitting file from a compilation.
Optional
noEmitHelpers?: boolean | nullDisable generating custom helper functions like __extends
in compiled output.
Optional
noEmitOnError?: boolean | nullDisable emitting files if any type checking errors are reported.
Optional
noErrorTruncation?: boolean | nullDisable truncating types in error messages.
Optional
noFallthroughCasesInSwitch?: boolean | nullEnable error reporting for fallthrough cases in switch statements.
Optional
noImplicitAny?: boolean | nullEnable error reporting for expressions and declarations with an implied any
type..
Optional
noImplicitOverride?: boolean | nullEnsure overriding members in derived classes are marked with an override modifier.
Optional
noImplicitReturns?: boolean | nullEnable error reporting for codepaths that do not explicitly return in a function.
Optional
noImplicitThis?: boolean | nullEnable error reporting when this
is given the type any
.
Optional
noImplicitUseStrict?: boolean | nullDisable adding 'use strict' directives in emitted JavaScript files.
Optional
noLib?: boolean | nullDisable including any library files, including the default lib.d.ts.
Optional
noPropertyAccessFromIndexSignature?: boolean | nullEnforces using indexed accessors for keys declared using an indexed type
Optional
noResolve?: boolean | nullDisallow import
s, require
s or <reference>
s from expanding the number of files TypeScript should add to a project.
Optional
noStrictGenericChecks?: boolean | nullDisable strict checking of generic signatures in function types.
Optional
noUncheckedIndexedAccess?: boolean | nullAdd undefined
to a type when accessed using an index.
Optional
noUncheckedSideEffectImports?: boolean | nullCheck side effect imports.
Optional
noUnusedLocals?: boolean | nullEnable error reporting when a local variable isn't read.
Optional
noUnusedParameters?: boolean | nullRaise an error when a function parameter isn't read
Optional
out?: string | nullDEPRECATED. Specify an output for the build. It is recommended to use outFile
instead.
Optional
outDir?: string | nullSpecify an output folder for all emitted files.
Optional
outFile?: string | nullSpecify a file that bundles all outputs into one JavaScript file. If declaration
is true, also designates a file that bundles all .d.ts output.
Optional
paths?: { [k: string]: string[] } | nullSpecify a set of entries that re-map imports to additional lookup locations.
Optional
plugins?: ({ name?: string | null; [k: string]: unknown } | null)[] | nullSpecify a list of language service plugins to include.
Optional
preserveConstEnums?: boolean | nullDisable erasing const enum
declarations in generated code.
Optional
preserveSymlinks?: boolean | nullDisable resolving symlinks to their realpath. This correlates to the same flag in node.
Optional
preserveValueImports?: boolean | nullPreserve unused imported values in the JavaScript output that would otherwise be removed
Optional
preserveWatchOutput?: boolean | nullDisable wiping the console in watch mode
Optional
pretty?: boolean | nullEnable color and formatting in output to make compiler errors easier to read
Optional
reactNamespace?: string | nullSpecify the object invoked for createElement
. This only applies when targeting react
JSX emit.
Optional
removeComments?: boolean | nullDisable emitting comments.
Optional
resolveJsonModule?: boolean | nullEnable importing .json files
Optional
resolvePackageJsonExports?: boolean | nullUse the package.json 'exports' field when resolving package imports.
Optional
resolvePackageJsonImports?: boolean | nullUse the package.json 'imports' field when resolving imports.
Optional
rewriteRelativeImportExtensions?: boolean | nullRewrite '.ts', '.tsx', '.mts', and '.cts' file extensions in relative import paths to their JavaScript equivalent in output files.
Optional
rootDir?: string | nullSpecify the root folder within your source files.
Optional
rootDirs?: (string | null)[] | nullAllow multiple folders to be treated as one when resolving modules.
Optional
skipDefaultLibCheck?: boolean | nullSkip type checking .d.ts files that are included with TypeScript.
Optional
skipLibCheck?: boolean | nullSkip type checking all .d.ts files.
Optional
sourceMap?: boolean | nullCreate source map files for emitted JavaScript files.
Optional
sourceRoot?: string | nullSpecify the root path for debuggers to find the reference source code.
Optional
strict?: boolean | nullEnable all strict type checking options.
Optional
strictBindCallApply?: boolean | nullCheck that the arguments for bind
, call
, and apply
methods match the original function.
Optional
strictBuiltinIteratorReturn?: boolean | nullBuilt-in iterators are instantiated with a 'TReturn' type of 'undefined' instead of 'any'.
Optional
strictFunctionTypes?: boolean | nullWhen assigning functions, check to ensure parameters and the return values are subtype-compatible.
Optional
strictNullChecks?: boolean | nullWhen type checking, take into account null
and undefined
.
Optional
strictPropertyInitialization?: boolean | nullCheck for class properties that are declared but not set in the constructor.
Optional
stripInternal?: boolean | nullDisable emitting declarations that have @internal
in their JSDoc comments.
Optional
suppressExcessPropertyErrors?: boolean | nullDisable reporting of excess property errors during the creation of object literals.
Optional
suppressImplicitAnyIndexErrors?: boolean | nullSuppress noImplicitAny
errors when indexing objects that lack index signatures.
Optional
target?: (Set the JavaScript language version for emitted JavaScript and include compatible library declarations.
Optional
traceResolution?: boolean | nullEnable tracing of the name resolution process. Requires TypeScript version 2.0 or later.
Optional
tsBuildInfoFile?: string | nullSpecify the folder for .tsbuildinfo incremental compilation files.
Optional
typeRoots?: (string | null)[] | nullSpecify multiple folders that act like ./node_modules/@types
.
Optional
types?: (string | null)[] | nullSpecify type package names to be included without being referenced in a source file.
Optional
useDefineForClassFields?: boolean | nullEmit ECMAScript-standard-compliant class fields.
Optional
useUnknownInCatchVariables?: boolean | nullDefault catch clause variables as unknown
instead of any
.
Optional
verbatimModuleSyntax?: boolean | nullDo 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.
Optional
watch?: boolean | nullWatch input files.
Optional
watchDirectory?: Specify the strategy for watching directories under systems that lack recursive file-watching functionality. Requires TypeScript version 3.8 or later.
Optional
watchFile?: Specify the strategy for watching individual files. Requires TypeScript version 3.8 or later.
Optional
allowArbitraryExtensions?: boolean | nullEnable importing files with any extension, provided a declaration file is present.
Optional
allowImportingTsExtensions?: boolean | nullAllow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set.
Optional
allowJs?: boolean | nullAllow JavaScript files to be a part of your program. Use the checkJS
option to get errors from these files.
Optional
allowSyntheticDefaultImports?: boolean | nullAllow 'import x from y' when a module doesn't have a default export.
Optional
allowUmdGlobalAccess?: boolean | nullAllow accessing UMD globals from modules.
Optional
allowUnreachableCode?: boolean | nullDisable error reporting for unreachable code.
Optional
allowUnusedLabels?: boolean | nullDisable error reporting for unused labels.
Optional
alwaysStrict?: boolean | nullEnsure 'use strict' is always emitted.
Optional
assumeChangesOnlyAffectDirectDependencies?: boolean | nullHave recompiles in '--incremental' and '--watch' assume that changes within a file will only affect files directly depending on it. Requires TypeScript version 3.8 or later.
Optional
baseUrl?: string | nullSpecify the base directory to resolve non-relative module names.
Optional
charset?: string | nullNo longer supported. In early versions, manually set the text encoding for reading files.
Optional
checkJs?: boolean | nullEnable error reporting in type-checked JavaScript files.
Optional
composite?: boolean | nullEnable constraints that allow a TypeScript project to be used with project references.
Optional
customConditions?: (string | null)[] | nullConditions to set in addition to the resolver-specific defaults when resolving imports.
Optional
declaration?: boolean | nullGenerate .d.ts files from TypeScript and JavaScript files in your project.
Optional
declarationDir?: string | nullSpecify the output directory for generated declaration files.
Optional
declarationMap?: boolean | nullCreate sourcemaps for d.ts files.
Optional
diagnostics?: boolean | nullOutput compiler performance information after building.
Optional
disableReferencedProjectLoad?: boolean | nullReduce the number of projects loaded automatically by TypeScript.
Optional
disableSizeLimit?: boolean | nullRemove the 20mb cap on total source code size for JavaScript files in the TypeScript language server.
Optional
disableSolutionSearching?: boolean | nullOpt a project out of multi-project reference checking when editing.
Optional
disableSourceOfProjectReferenceRedirect?: boolean | nullDisable preferring source files instead of declaration files when referencing composite projects
Optional
downlevelIteration?: boolean | nullEmit more compliant, but verbose and less performant JavaScript for iteration.
Optional
emitBOM?: boolean | nullEmit a UTF-8 Byte Order Mark (BOM) in the beginning of output files.
Optional
emitDeclarationOnly?: boolean | nullOnly output d.ts files and not JavaScript files.
Optional
emitDecoratorMetadata?: boolean | nullEmit design-type metadata for decorated declarations in source files.
Optional
erasableSyntaxOnly?: boolean | nullDo not allow runtime constructs that are not part of ECMAScript.
Optional
esModuleInterop?: boolean | nullEmit additional JavaScript to ease support for importing CommonJS modules. This enables allowSyntheticDefaultImports
for type compatibility.
Optional
exactOptionalPropertyTypes?: boolean | nullDifferentiate between undefined and not present when type checking
Optional
experimentalDecorators?: boolean | nullEnable experimental support for TC39 stage 2 draft decorators.
Optional
extendedDiagnostics?: boolean | nullOutput more detailed compiler performance information after building.
Optional
fallbackPolling?: Specify the polling strategy to use when the system runs out of or doesn't support native file watchers. Requires TypeScript version 3.8 or later.
Optional
forceConsistentCasingInFileNames?: boolean | nullEnsure that casing is correct in imports.
Optional
generateCpuProfile?: string | nullEmit a v8 CPU profile of the compiler run for debugging.
Optional
importHelpers?: boolean | nullAllow importing helper functions from tslib once per project, instead of including them per-file.
Optional
importsNotUsedAsValues?: "remove" | "preserve" | "error"Specify emit/checking behavior for imports that are only used for types.
Optional
incremental?: boolean | nullEnable incremental compilation. Requires TypeScript version 3.4 or later.
Optional
inlineSourceMap?: boolean | nullInclude sourcemap files inside the emitted JavaScript.
Optional
inlineSources?: boolean | nullInclude source code in the sourcemaps inside the emitted JavaScript.
Optional
isolatedDeclarations?: boolean | nullRequire sufficient annotation on exports so other tools can trivially generate declaration files.
Optional
isolatedModules?: boolean | nullEnsure that each file can be safely transpiled without relying on other imports.
Optional
jsx?: "preserve" | "react" | "react-jsx" | "react-jsxdev" | "react-native"Specify what JSX code is generated.
Optional
jsxFactory?: string | nullSpecify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'
Optional
jsxFragmentFactory?: string | nullSpecify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'.
Optional
jsxImportSource?: string | nullSpecify module specifier used to import the JSX factory functions when using jsx: react-jsx
.
Optional
keyofStringsOnly?: boolean | nullMake keyof only return strings instead of string, numbers or symbols. Legacy option.
Optional
lib?: Specify a set of bundled library declaration files that describe the target runtime environment.
Optional
libReplacement?: boolean | nullEnable lib replacement.
Optional
listEmittedFiles?: boolean | nullPrint the names of emitted files after a compilation.
Optional
listFiles?: boolean | nullPrint all of the files read during the compilation.
Optional
listFilesOnly?: boolean | nullPrint names of files that are part of the compilation and then stop processing.
Optional
mapRoot?: string | nullSpecify the location where debugger should locate map files instead of generated locations.
Optional
maxNodeModuleJsDepth?: number | nullSpecify the maximum folder depth used for checking JavaScript files from node_modules
. Only applicable with allowJs
.
Optional
module?: (Optional
moduleDetection?: "auto" | "legacy" | "force"Specify how TypeScript determine a file as module.
Optional
moduleResolution?: (Optional
newLine?: ("crlf" | "lf" | { [k: string]: unknown }) & (Optional
noCheck?: boolean | nullDisable full type checking (only critical parse and emit errors will be reported)
Optional
noEmit?: boolean | nullDisable emitting file from a compilation.
Optional
noEmitHelpers?: boolean | nullDisable generating custom helper functions like __extends
in compiled output.
Optional
noEmitOnError?: boolean | nullDisable emitting files if any type checking errors are reported.
Optional
noErrorTruncation?: boolean | nullDisable truncating types in error messages.
Optional
noFallthroughCasesInSwitch?: boolean | nullEnable error reporting for fallthrough cases in switch statements.
Optional
noImplicitAny?: boolean | nullEnable error reporting for expressions and declarations with an implied any
type..
Optional
noImplicitOverride?: boolean | nullEnsure overriding members in derived classes are marked with an override modifier.
Optional
noImplicitReturns?: boolean | nullEnable error reporting for codepaths that do not explicitly return in a function.
Optional
noImplicitThis?: boolean | nullEnable error reporting when this
is given the type any
.
Optional
noImplicitUseStrict?: boolean | nullDisable adding 'use strict' directives in emitted JavaScript files.
Optional
noLib?: boolean | nullDisable including any library files, including the default lib.d.ts.
Optional
noPropertyAccessFromIndexSignature?: boolean | nullEnforces using indexed accessors for keys declared using an indexed type
Optional
noResolve?: boolean | nullDisallow import
s, require
s or <reference>
s from expanding the number of files TypeScript should add to a project.
Optional
noStrictGenericChecks?: boolean | nullDisable strict checking of generic signatures in function types.
Optional
noUncheckedIndexedAccess?: boolean | nullAdd undefined
to a type when accessed using an index.
Optional
noUncheckedSideEffectImports?: boolean | nullCheck side effect imports.
Optional
noUnusedLocals?: boolean | nullEnable error reporting when a local variable isn't read.
Optional
noUnusedParameters?: boolean | nullRaise an error when a function parameter isn't read
Optional
out?: string | nullDEPRECATED. Specify an output for the build. It is recommended to use outFile
instead.
Optional
outDir?: string | nullSpecify an output folder for all emitted files.
Optional
outFile?: string | nullSpecify a file that bundles all outputs into one JavaScript file. If declaration
is true, also designates a file that bundles all .d.ts output.
Optional
paths?: { [k: string]: string[] } | nullSpecify a set of entries that re-map imports to additional lookup locations.
Optional
plugins?: ({ name?: string | null; [k: string]: unknown } | null)[] | nullSpecify a list of language service plugins to include.
Optional
preserveConstEnums?: boolean | nullDisable erasing const enum
declarations in generated code.
Optional
preserveSymlinks?: boolean | nullDisable resolving symlinks to their realpath. This correlates to the same flag in node.
Optional
preserveValueImports?: boolean | nullPreserve unused imported values in the JavaScript output that would otherwise be removed
Optional
preserveWatchOutput?: boolean | nullDisable wiping the console in watch mode
Optional
pretty?: boolean | nullEnable color and formatting in output to make compiler errors easier to read
Optional
reactNamespace?: string | nullSpecify the object invoked for createElement
. This only applies when targeting react
JSX emit.
Optional
removeComments?: boolean | nullDisable emitting comments.
Optional
resolveJsonModule?: boolean | nullEnable importing .json files
Optional
resolvePackageJsonExports?: boolean | nullUse the package.json 'exports' field when resolving package imports.
Optional
resolvePackageJsonImports?: boolean | nullUse the package.json 'imports' field when resolving imports.
Optional
rewriteRelativeImportExtensions?: boolean | nullRewrite '.ts', '.tsx', '.mts', and '.cts' file extensions in relative import paths to their JavaScript equivalent in output files.
Optional
rootDir?: string | nullSpecify the root folder within your source files.
Optional
rootDirs?: (string | null)[] | nullAllow multiple folders to be treated as one when resolving modules.
Optional
skipDefaultLibCheck?: boolean | nullSkip type checking .d.ts files that are included with TypeScript.
Optional
skipLibCheck?: boolean | nullSkip type checking all .d.ts files.
Optional
sourceMap?: boolean | nullCreate source map files for emitted JavaScript files.
Optional
sourceRoot?: string | nullSpecify the root path for debuggers to find the reference source code.
Optional
strict?: boolean | nullEnable all strict type checking options.
Optional
strictBindCallApply?: boolean | nullCheck that the arguments for bind
, call
, and apply
methods match the original function.
Optional
strictBuiltinIteratorReturn?: boolean | nullBuilt-in iterators are instantiated with a 'TReturn' type of 'undefined' instead of 'any'.
Optional
strictFunctionTypes?: boolean | nullWhen assigning functions, check to ensure parameters and the return values are subtype-compatible.
Optional
strictNullChecks?: boolean | nullWhen type checking, take into account null
and undefined
.
Optional
strictPropertyInitialization?: boolean | nullCheck for class properties that are declared but not set in the constructor.
Optional
stripInternal?: boolean | nullDisable emitting declarations that have @internal
in their JSDoc comments.
Optional
suppressExcessPropertyErrors?: boolean | nullDisable reporting of excess property errors during the creation of object literals.
Optional
suppressImplicitAnyIndexErrors?: boolean | nullSuppress noImplicitAny
errors when indexing objects that lack index signatures.
Optional
target?: (Optional
traceResolution?: boolean | nullEnable tracing of the name resolution process. Requires TypeScript version 2.0 or later.
Optional
tsBuildInfoFile?: string | nullSpecify the folder for .tsbuildinfo incremental compilation files.
Optional
typeRoots?: (string | null)[] | nullSpecify multiple folders that act like ./node_modules/@types
.
Optional
types?: (string | null)[] | nullSpecify type package names to be included without being referenced in a source file.
Optional
useDefineForClassFields?: boolean | nullEmit ECMAScript-standard-compliant class fields.
Optional
useUnknownInCatchVariables?: boolean | nullDefault catch clause variables as unknown
instead of any
.
Optional
verbatimModuleSyntax?: boolean | nullDo 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.
Optional
watch?: boolean | nullWatch input files.
Optional
watchDirectory?: Specify the strategy for watching directories under systems that lack recursive file-watching functionality. Requires TypeScript version 3.8 or later.
Optional
watchFile?: Specify the strategy for watching individual files. Requires TypeScript version 3.8 or later.
Instructs the TypeScript compiler how to compile .ts files.