docs: Add some JSDocs

editor.planx.uk/src/@planx/components/Pay/Public/FeeBreakdown/useFeeBreakdown.tsx

@@ -4,6 +4,13 @@ import { useStore } from "pages/FlowEditor/lib/store";
 import { FeeBreakdown } from "./types";
 import { createPassportSchema } from "./utils";
 
+/**
+ * Parses the users's Passport for data variables associated with their fee
+ * Currently relies on static `application.fee.x` variables
+ *
+ * If fee variables not found, or not successfully parsed, we do not show the user a fee breakdown
+ * Instead an internal error will be raised allowing us to correct the flow content
+ */
 export const useFeeBreakdown = (): FeeBreakdown | undefined => {
   const [passportData, sessionId] = useStore((state) => [
     state.computePassport().data,
@@ -12,7 +19,6 @@ export const useFeeBreakdown = (): FeeBreakdown | undefined => {
   const schema = createPassportSchema();
   const result = schema.safeParse(passportData);
 
-  // Unable to parse fee data from passport, do not show FeeBreakdown component
   if (!result.success) {
     logger.notify(
       `Failed to parse fee breakdown data from passport for session ${sessionId}. Error: ${result.error}`,

editor.planx.uk/src/@planx/components/Pay/Public/FeeBreakdown/utils.ts

@@ -5,11 +5,18 @@ import { FeeBreakdown, PassportFeeFields } from "./types";
 export const toNumber = (input: number | [number]) =>
   Array.isArray(input) ? input[0] : input;
 
+/**
+ * A "reduction" is the sum of the difference between calculated and payable
+ * This is not currently broken down further into component parts, or as exemptions or reductions
+ */
 export const calculateReduction = (data: PassportFeeFields) =>
   data["application.fee.calculated"]
     ? data["application.fee.calculated"] - data["application.fee.payable"]
     : 0;
 
+/**
+ * Transform Passport data to a FeeBreakdown shape
+ */
 export const toFeeBreakdown = (data: PassportFeeFields): FeeBreakdown => ({
   applicationFee:
     data["application.fee.calculated"] || data["application.fee.payable"],