adding jsdoc

src/tiny-invariant.ts

@@ -1,13 +1,28 @@
 const isProduction: boolean = process.env.NODE_ENV === 'production';
 const prefix: string = 'Invariant failed';
 
-// Throw an error if the condition fails
-// Strip out error messages for production
-// > Not providing an inline default argument for message as the result is smaller
+/**
+ * `invariant` is used to [assert](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions) that the `condition` is [truthy](https://github.com/getify/You-Dont-Know-JS/blob/bdbe570600d4e1107d0b131787903ca1c9ec8140/up%20%26%20going/ch2.md#truthy--falsy).
+ *
+ * 💥 `invariant` will `throw` an `Error` if the `condition` is [falsey](https://github.com/getify/You-Dont-Know-JS/blob/bdbe570600d4e1107d0b131787903ca1c9ec8140/up%20%26%20going/ch2.md#truthy--falsy)
+ *
+ * 🤏 `message`s are not displayed in production environments to help keep bundles small
+ *
+ * @example
+ *
+ * ```ts
+ * const value: Person | null = { name: 'Alex' };
+ * invariant(value, 'Expected value to be a person');
+ * // type of `value`` has been narrowed to `Person`
+ * ```
+ */
 export default function invariant(
   condition: any,
-  // Can provide a string, or a function that returns a string for cases where
-  // the message takes a fair amount of effort to compute
+  // Not providing an inline default argument for message as the result is smaller
+  /**
+   * Can provide a string, or a function that returns a string for cases where
+   * the message takes a fair amount of effort to compute
+   */
   message?: string | (() => string),
 ): asserts condition {
   if (condition) {