Update descriptions for all compiler options

[orta]

Back at the end of 2020 we had a series of meetings going through all the tsconfig options, revising their descriptions and making them all consistent. They were then moved into the website, with the goal of bringing them upstream later. Today is that later, heh.

Overview of the new descriptions:

❯ node built/local/tsc.js --help --all
Version 4.4.0-dev
Syntax: tsc [options] [file...]
Examples: tsc hello.ts
tsc --outFile file.js file.ts
tsc @args.txt
tsc --build tsconfig.json
Options:
--all Show all compiler options.
--allowJs Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files.
--allowSyntheticDefaultImports Allow 'import x from y' when a module doesn't have a default export.
--allowUmdGlobalAccess Allow accessing UMD globals from modules.
--allowUnreachableCode Disable error reporting for unreachable code.
--allowUnusedLabels Disable error reporting for unused labels.
--alwaysStrict Ensure 'use strict' is always emitted.
--assumeChangesOnlyAffectDirectDependencies Have recompiles in projects that use `incremental` and `watch` mode assume that changes within a file will only affect files directly depending on it.
--baseUrl Specify the base directory to resolve non-relative module names.
-b, --build Build one or more projects and their dependencies, if out of date
--charset No longer supported. In early versions, manually set the text encoding for reading files.
--checkJs Enable error reporting in type-checked JavaScript files.
--composite Enable constraints that allow a TypeScript project to be used with project references.
-d, --declaration Generate .d.ts files from TypeScript and JavaScript files in your project.
--declarationDir DIRECTORY Specify the output directory for generated declaration files.
--declarationMap Create sourcemaps for d.ts files.
--diagnostics Output compiler performance information after building.
--disableReferencedProjectLoad Reduce the number of projects loaded automatically by TypeScript.
--disableSizeLimit Remove the 20mb cap on total source code size for JavaScript files in the TypeScript language server.
--disableSolutionSearching Opt a project out of multi-project reference checking when editing.
--disableSourceOfProjectReferenceRedirect Disable preferring source files instead of declaration files when referencing composite projects
--downlevelIteration Emit more compliant, but verbose and less performant JavaScript for iteration.
--emitBOM Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files.
--emitDeclarationOnly Only output d.ts files and not JavaScript files.
--emitDecoratorMetadata Emit design-type metadata for decorated declarations in source files.
--esModuleInterop Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility.
--experimentalDecorators Enable experimental support for TC39 stage 2 draft decorators.
--explainFiles Print files read during the compilation including why it was included.
--extendedDiagnostics Output more detailed compiler performance information after building.
--forceConsistentCasingInFileNames Ensure that casing is correct in imports.
--generateCpuProfile FILE OR DIRECTORY Emit a v8 CPU profile of the compiler run for debugging.
--generateTrace DIRECTORY Generates an event trace and a list of types.
-h, --help Print this message.
--importHelpers Allow importing helper functions from tslib once per project, instead of including them per-file.
--importsNotUsedAsValues Specify emit/checking behavior for imports that are only used for types
-i, --incremental Enable incremental compilation
--init Initializes a TypeScript project and creates a tsconfig.json file.
--inlineSourceMap Include sourcemap files inside the emitted JavaScript.
--inlineSources Include source code in the sourcemaps inside the emitted JavaScript.
--isolatedModules Ensure that each file can be safely transpiled without relying on other imports.
--jsx KIND Specify what JSX code is generated.
--jsxFactory Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'
--jsxFragmentFactory Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'.
--jsxImportSource Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.`
--keyofStringsOnly Make keyof only return strings instead of string, numbers or symbols. Legacy option.
--lib Specify a set of bundled library declaration files that describe the target runtime environment.
'es5' 'es6' 'es2015' 'es7' 'es2016' 'es2017' 'es2018' 'es2019' 'es2020' 'es2021' 'esnext' 'dom' 'dom.iterable' 'webworker' 'webworker.importscripts' 'webworker.iterable' 'scripthost' 'es2015.core' 'es2015.collection' 'es2015.generator' 'es2015.iterable' 'es2015.promise' 'es2015.proxy' 'es2015.reflect' 'es2015.symbol' 'es2015.symbol.wellknown' 'es2016.array.include' 'es2017.object' 'es2017.sharedmemory' 'es2017.string' 'es2017.intl' 'es2017.typedarrays' 'es2018.asyncgenerator' 'es2018.asynciterable' 'es2018.intl' 'es2018.promise' 'es2018.regexp' 'es2019.array' 'es2019.object' 'es2019.string' 'es2019.symbol' 'es2020.bigint' 'es2020.promise' 'es2020.sharedmemory' 'es2020.string' 'es2020.symbol.wellknown' 'es2020.intl' 'es2021.promise' 'es2021.string' 'es2021.weakref' 'esnext.array' 'esnext.symbol' 'esnext.asynciterable' 'esnext.intl' 'esnext.bigint' 'esnext.string' 'esnext.promise' 'esnext.weakref' --listEmittedFiles Print the names of emitted files after a compilation.
--listFiles Print all of the files read during the compilation.
--listFilesOnly Print names of files that are part of the compilation and then stop processing.
--locale Set the language of the messaging from TypeScript. This does not affect emit.
--mapRoot LOCATION Specify the location where debugger should locate map files instead of generated locations.
--maxNodeModuleJsDepth Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`.
-m KIND, --module KIND Specify what module code is generated.
--moduleResolution STRATEGY Specify how TypeScript looks up a file from a given module specifier.
--newLine NEWLINE Set the newline character for emitting files.
--noEmit Disable emitting file from a compilation.
--noEmitHelpers Disable generating custom helper functions like `__extends` in compiled output.
--noEmitOnError Disable emitting files if any type checking errors are reported.
--noErrorTruncation Disable truncating types in error messages.
--noFallthroughCasesInSwitch Enable error reporting for fallthrough cases in switch statements.
--noImplicitAny Enable error reporting for expressions and declarations with an implied `any` type..
--noImplicitOverride Add `undefined` to a type when accessed using an index.
--noImplicitReturns Enable error reporting for codepaths that do not explicitly return in a function.
--noImplicitThis Enable error reporting when `this` is given the type `any`.
--noImplicitUseStrict Disable adding 'use strict' directives in emitted JavaScript files.
--noLib Disable including any library files, including the default lib.d.ts.
--noPropertyAccessFromIndexSignature Enforces using indexed accessors for keys declared using an indexed type
--noResolve Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project.
--noStrictGenericChecks Disable strict checking of generic signatures in function types.
--noUncheckedIndexedAccess Include 'undefined' in index signature results
--noUnusedLocals Enable error reporting when a local variables aren't read.
--noUnusedParameters Raise an error when a function parameter isn't read
--out FILE Deprecated setting. Use `outFile` instead.
--outDir DIRECTORY Specify an output folder for all emitted files.
--outFile FILE Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output.
--paths Specify a set of entries that re-map imports to additional lookup locations.
--plugins List of language service plugins.
--preserveConstEnums Disable erasing `const enum` declarations in generated code.
--preserveSymlinks Disable resolving symlinks to their realpath. This correlates to the same flag in node.
--preserveWatchOutput Disable wiping the console in watch mode
--pretty Enable color and formatting in output to make compiler errors easier to read
-p FILE OR DIRECTORY, --project FILE OR DIRECTORY Compile the project given the path to its configuration file, or to a folder with a 'tsconfig.json'.
--reactNamespace Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit.
--removeComments Disable emitting comments.
--resolveJsonModule Enable importing .json files
--rootDir LOCATION Specify the root folder within your source files.
--rootDirs Allow multiple folders to be treated as one when resolving modules.
--showConfig Print the final configuration instead of building.
--skipDefaultLibCheck Skip type checking .d.ts files that are included with TypeScript.
--skipLibCheck Skip type checking all .d.ts files.
--sourceMap Create source map files for emitted JavaScript files.
--sourceRoot LOCATION Specify the root path for debuggers to find the reference source code.
--strict Enable all strict type-checking options.
--strictBindCallApply Check that the arguments for `bind`, `call`, and `apply` methods match the original function.
--strictFunctionTypes When assigning functions, check to ensure parameters and the return values are subtype-compatible.
--strictNullChecks When type checking, take into account `null` and `undefined`.
--strictOptionalProperties Enable strict checking of optional properties.
--strictPropertyInitialization Check for class properties that are declared but not set in the constructor.
--stripInternal Disable emitting declarations that have `@internal` in their JSDoc comments.
--suppressExcessPropertyErrors Disable reporting of excess property errors during the creation of object literals.
--suppressImplicitAnyIndexErrors Suppress `noImplicitAny` errors when indexing objects that lack index signatures.
-t VERSION, --target VERSION Set the JavaScript language version for emitted JavaScript and include compatible library declarations.
--traceResolution Log paths used during the `moduleResolution` process.
--tsBuildInfoFile FILE Specify the folder for .tsbuildinfo incremental compilation files.
--typeRoots Specify multiple folders that act like `./node_modules/@types`.
--types Specify type package names to be included without being referenced in a source file.
--useDefineForClassFields Emit ECMAScript-standard-compliant class fields.
-v, --version Print the compiler's version.
-w, --watch Watch input files.
@<file> Insert command line options and files from a file.

[orta]

Note: I haven't removed all the unused diags, I'm waiting on getting #44324 merged so that I can just do it in a single pass rather than have this collect merge conflicts with time

[orta]

Linking my script for grabbing a bunch of these from the site and syncing them: https://gist.github.com/orta/f8f94b4b52eba847d2cf016a1d281730