Targets · TypeScript · Reserved words

Reserved words

TypeScript keeps a set of words for its own syntax, so a program cannot use them as names. When a Program name collides with one, the renderer appends a single underscore — class becomes class_ — so the program keeps the name it chose and the output still compiles. Because _ is illegal in a Program identifier, the escape can never collide with a name a program actually chose. TypeScript reserves everything JavaScript does, plus its own type-level words.

How a Program becomes TypeScript, in parts. Start with the introduction, then follow each part into the rendered output and the runtime it links against.

Introduction — what the TypeScript target is, and how to read the rest of this section.
Capabilities — which high-level features are possible, built in or through a library.
Example — a full program using every keyword, and the TypeScript it renders to.
Naming considerations — how Program's dotted names are carried into TypeScript.
Entry point — starting a program and attaching it to a root element.
Drivers — the native drivers that provide the interface, animation and network.
Runtime — the Reactive and Context machinery the rendered code links against.
Native modules — the hand-written JavaScript behind NATIVE functions.
Keywords — how each of Program's keywords renders to TypeScript.
Project setup — the files and commands to build and run the rendered program.
Reserved words — the words TypeScript keeps for itself, and how a colliding name is escaped.

The full list

Every word TypeScript reserves, with the identifier a colliding Program name is escaped to. The rule is uniform — append a single _:

Reserved word	Rendered identifier
`await`	`await_`
`break`	`break_`
`case`	`case_`
`catch`	`catch_`
`class`	`class_`
`const`	`const_`
`continue`	`continue_`
`debugger`	`debugger_`
`default`	`default_`
`delete`	`delete_`
`do`	`do_`
`else`	`else_`
`enum`	`enum_`
`export`	`export_`
`extends`	`extends_`
`false`	`false_`
`finally`	`finally_`
`for`	`for_`
`function`	`function_`
`if`	`if_`
`import`	`import_`
`in`	`in_`
`instanceof`	`instanceof_`
`new`	`new_`
`null`	`null_`
`return`	`return_`
`super`	`super_`
`switch`	`switch_`
`this`	`this_`
`throw`	`throw_`
`true`	`true_`
`try`	`try_`
`typeof`	`typeof_`
`var`	`var_`
`void`	`void_`
`while`	`while_`
`with`	`with_`
`yield`	`yield_`
`let`	`let_`
`static`	`static_`
`implements`	`implements_`
`interface`	`interface_`
`package`	`package_`
`private`	`private_`
`protected`	`protected_`
`public`	`public_`
`abstract`	`abstract_`
`any`	`any_`
`as`	`as_`
`asserts`	`asserts_`
`async`	`async_`
`bigint`	`bigint_`
`boolean`	`boolean_`
`constructor`	`constructor_`
`declare`	`declare_`
`get`	`get_`
`infer`	`infer_`
`is`	`is_`
`keyof`	`keyof_`
`module`	`module_`
`namespace`	`namespace_`
`never`	`never_`
`number`	`number_`
`object`	`object_`
`of`	`of_`
`out`	`out_`
`override`	`override_`
`readonly`	`readonly_`
`require`	`require_`
`satisfies`	`satisfies_`
`set`	`set_`
`string`	`string_`
`symbol`	`symbol_`
`type`	`type_`
`undefined`	`undefined_`
`unique`	`unique_`
`unknown`	`unknown_`

Reserved words

Contents

The full list