add jsdocs

Author: yeonjuan

src/compiler/types.ts

@@ -4968,6 +4968,16 @@ export interface TypeChecker {
     getWidenedLiteralType(type: Type): Type;
     /** @internal */
     getPromisedTypeOfPromise(promise: Type, errorNode?: Node): Type | undefined;
+    /**
+     * Gets the "awaited type" of a type.
+     *
+     * The "awaited type" of an expression is its "promised type" if the expression is a
+     * Promise-like type; otherwise, it is the type of the expression. If the "promised
+     * type" is itself a Promise-like, the "promised type" is recursively unwrapped until a
+     * non-promise type is found.
+     *
+     * This is used to reflect the runtime behavior of the `await` keyword.
+     */
     getAwaitedType(type: Type): Type | undefined;
     /** @internal */
     isEmptyAnonymousObjectType(type: Type): boolean;

tests/baselines/reference/api/typescript.d.ts

@@ -6070,6 +6070,16 @@ declare namespace ts {
         getBaseTypes(type: InterfaceType): BaseType[];
         getBaseTypeOfLiteralType(type: Type): Type;
         getWidenedType(type: Type): Type;
+        /**
+         * Gets the "awaited type" of a type.
+         *
+         * The "awaited type" of an expression is its "promised type" if the expression is a
+         * Promise-like type; otherwise, it is the type of the expression. If the "promised
+         * type" is itself a Promise-like, the "promised type" is recursively unwrapped until a
+         * non-promise type is found.
+         *
+         * This is used to reflect the runtime behavior of the `await` keyword.
+         */
         getAwaitedType(type: Type): Type | undefined;
         getReturnTypeOfSignature(signature: Signature): Type;
         getNullableType(type: Type, flags: TypeFlags): Type;