move some comments to another place

Author: AbanoubGhadban

node_package/src/serverRenderReactComponent.ts

@@ -42,7 +42,7 @@ function processServerRenderHash(result: ServerRenderResult, options: RenderOpti
       console.log(`ROUTER REDIRECT: ${options.componentName} to dom node with id: ${options.domNodeId}, redirect to ${redirectPath}`);
     }
     // For redirects on server rendering, we can't stop Rails from returning the same result.
-    // Possibly, someday, we could have the rails server redirect.
+    // Possibly, someday, we could have the Rails server redirect.
     htmlResult = '';
   } else {
     htmlResult = result.renderedHtml as string;
@@ -51,14 +51,14 @@ function processServerRenderHash(result: ServerRenderResult, options: RenderOpti
   return { result: htmlResult, hasErrors };
 }
 
-function processPromise(result: Promise<unknown>, renderingReturnsPromises: boolean): Promise<string> | string {
+function processPromise(result: Promise<string>, renderingReturnsPromises: boolean): Promise<string> | string {
   if (!renderingReturnsPromises) {
     console.error('Your render function returned a Promise, which is only supported by a node renderer, not ExecJS.');
     // If the app is using server rendering with ExecJS, then the promise will not be awaited.
     // And when a promise is passed to JSON.stringify, it will be converted to '{}'.
     return '{}';
   }
-  return result as Promise<string>;
+  return result;
 }
 
 function processReactElement(result: ReactElement): string {

node_package/src/types/index.ts

@@ -43,6 +43,30 @@ type CreateReactOutputResult = ServerRenderResult | ReactElement | Promise<strin
 
 type RenderFunctionResult = ReactComponent | ServerRenderResult | Promise<string>;
 
+/**
+ * Render functions are used to create dynamic React components or server-rendered HTML with side effects.
+ * They receive two arguments: props and railsContext.
+ * 
+ * @param props - The component props passed to the render function
+ * @param railsContext - The Rails context object containing environment information
+ * @returns A string, React component, React element, or a Promise resolving to a string
+ * 
+ * @remarks
+ * To distinguish a render function from a React Function Component:
+ * 1. Ensure it accepts two parameters (props and railsContext), even if railsContext is unused, or
+ * 2. Set the `renderFunction` property to `true` on the function object.
+ * 
+ * If neither condition is met, it will be treated as a React Function Component,
+ * and ReactDOMServer will attempt to render it.
+ * 
+ * @example
+ * // Option 1: Two-parameter function
+ * const renderFunction = (props, railsContext) => { ... };
+ * 
+ * // Option 2: Using renderFunction property
+ * const anotherRenderFunction = (props) => { ... };
+ * anotherRenderFunction.renderFunction = true;
+ */
 interface RenderFunction {
   (props?: any, railsContext?: RailsContext, domNodeId?: string): RenderFunctionResult;
   // We allow specifying that the function is RenderFunction and not a React Function Component
@@ -67,10 +91,10 @@ export type { // eslint-disable-line import/prefer-default-export
 export interface RegisteredComponent {
   name: string;
   component: ReactComponentOrRenderFunction;
-  // Indicates if the registered component is a Render-function.
-  // Render-functions receive two arguments: props and railsContext.
-  // They should return a string, React component, React element, or a Promise.
-  // These functions are used to create dynamic React components or server-rendered HTML.
+  /**
+   * Indicates if the registered component is a RenderFunction
+   * @see RenderFunction for more details on its behavior and usage.
+   */
   renderFunction: boolean;
   // Indicates if the registered component is a Renderer function.
   // Renderer function handles DOM rendering or hydration with 3 args: (props, railsContext, domNodeId)