create defined types, update Check types, update build

gulpfile.js

@@ -1198,12 +1198,19 @@ function generateTypeScriptDefinitions(
     .replace(/^(\s*)(export )?const enum (\S+) {(\s*)$/gm, "$1$2enum $3 {$4")
     // Replace JSDoc generation version of defined with an improved version using TS type predicates
     .replace(
-      /defined\(value: any\): boolean/gm,
-      "defined<Type>(value: Type): value is NonNullable<Type>",
+      /\n?export function defined\(value: any\): boolean;/gm,
+      `\n${readFileSync("./packages/engine/Source/Core/defined.d.ts")
+        .toString()
+        .replace(/\n*\/\*.*?\*\/\n*/gms, "")
+        .replace("export default", "export")}`,
     )
+    // Replace JSDoc generation version of Check with one that asserts the type of variables after called
     .replace(
       /\/\*\*[\*\s\w]*?\*\/\nexport const Check: any;/m,
-      `\n${readFileSync("./packages/engine/Source/Core/Check.d.ts").toString()}`,
+      `\n${readFileSync("./packages/engine/Source/Core/Check.d.ts")
+        .toString()
+        .replace(/export default.*\n/, "")
+        .replace("const Check", "export const Check")}`,
     )
     // Fix https://github.com/CesiumGS/cesium/issues/10498 so we can use the rest parameter expand tuple
     .replace(
@@ -1405,12 +1412,19 @@ function createTypeScriptDefinitions() {
     .replace(/^(\s*)(export )?const enum (\S+) {(\s*)$/gm, "$1$2enum $3 {$4")
     // Replace JSDoc generation version of defined with an improved version using TS type predicates
     .replace(
-      /defined\(value: any\): boolean/gm,
-      "defined<Type>(value: Type): value is NonNullable<Type>",
+      /\n?export function defined\(value: any\): boolean;/gm,
+      `\n${readFileSync("./packages/engine/Source/Core/defined.d.ts")
+        .toString()
+        .replace(/\n*\/\*.*?\*\/\n*/gms, "")
+        .replace("export default", "export")}`,
     )
+    // Replace JSDoc generation version of Check with one that asserts the type of variables after called
     .replace(
       /\/\*\*[\*\s\w]*?\*\/\nexport const Check: any;/m,
-      `\n${readFileSync("./packages/engine/Source/Core/Check.d.ts").toString()}`,
+      `\n${readFileSync("./packages/engine/Source/Core/Check.d.ts")
+        .toString()
+        .replace(/export default.*\n/, "")
+        .replace("const Check", "export const Check")}`,
     )
     // Fix https://github.com/CesiumGS/cesium/issues/10498 to have rest parameter expand tuple
     .replace(

packages/engine/Source/Core/Check.d.ts

@@ -2,7 +2,7 @@
  * Contains functions for checking that supplied arguments are of a specified type
  * or meet specified conditions
  */
-export const Check: {
+const Check: {
   /**
    * Throws if test is not defined
    *
@@ -125,3 +125,4 @@ export const Check: {
     };
   };
 };
+export default Check;

packages/engine/Source/Core/defined.d.ts

@@ -0,0 +1,11 @@
+/**
+ * @example
+ * if (Cesium.defined(positions)) {
+ *      doSomething();
+ * } else {
+ *      doSomethingElse();
+ * }
+ * @param value - The object.
+ * @returns Returns true if the object is defined, returns false otherwise.
+ */
+export default function defined<Type>(value: Type): value is NonNullable<Type>;