diff --git a/src/amounts.ts b/src/amounts.ts
index fafbcb3ef..280cd636c 100644
--- a/src/amounts.ts
+++ b/src/amounts.ts
@@ -19,16 +19,19 @@
  * Types and helper functions for dealing with Taler amounts.
  */
 
+
 /**
  * Imports.
  */
 import { Checkable } from "./checkable";
 
+
 /**
  * Number of fractional units that one value unit represents.
  */
 export const fractionalBase = 1e8;
 
+
 /**
  * Non-negative financial amount.  Fractional values are expressed as multiples
  * of 1e-8.
@@ -60,6 +63,7 @@ export class AmountJson {
   static checked: (obj: any) => AmountJson;
 }
 
+
 /**
  * Result of a possibly overflowing operation.
  */
@@ -74,6 +78,7 @@ export interface Result {
   saturated: boolean;
 }
 
+
 /**
  * Get the largest amount that is safely representable.
  */
@@ -85,6 +90,7 @@ export function getMaxAmount(currency: string): AmountJson {
   };
 }
 
+
 /**
  * Get an amount that represents zero units of a currency.
  */
@@ -96,6 +102,7 @@ export function getZero(currency: string): AmountJson {
   };
 }
 
+
 /**
  * Add two amounts.  Return the result and whether
  * the addition overflowed.  The overflow is always handled
@@ -124,6 +131,7 @@ export function add(first: AmountJson, ...rest: AmountJson[]): Result {
   return { amount: { currency, value, fraction }, saturated: false };
 }
 
+
 /**
  * Subtract two amounts.  Return the result and whether
  * the subtraction overflowed.  The overflow is always handled
@@ -158,6 +166,7 @@ export function sub(a: AmountJson, ...rest: AmountJson[]): Result {
   return { amount: { currency, value, fraction }, saturated: false };
 }
 
+
 /**
  * Compare two amounts.  Returns 0 when equal, -1 when a < b
  * and +1 when a > b.  Throws when currencies don't match.
@@ -186,6 +195,7 @@ export function cmp(a: AmountJson, b: AmountJson): number {
   }
 }
 
+
 /**
  * Create a copy of an amount.
  */
@@ -197,6 +207,7 @@ export function copy(a: AmountJson): AmountJson {
   };
 }
 
+
 /**
  * Divide an amount.  Throws on division by zero.
  */
@@ -215,6 +226,7 @@ export function divide(a: AmountJson, n: number): AmountJson {
   };
 }
 
+
 /**
  * Check if an amount is non-zero.
  */
@@ -222,6 +234,7 @@ export function isNonZero(a: AmountJson): boolean {
   return a.value > 0 || a.fraction > 0;
 }
 
+
 /**
  * Parse an amount like 'EUR:20.5' for 20 Euros and 50 ct.
  */
@@ -237,6 +250,11 @@ export function parse(s: string): AmountJson|undefined {
   };
 }
 
+
+/**
+ * Parse amount in standard string form (like 'EUR:20.5'),
+ * throw if the input is not a valid amount.
+ */
 export function parseOrThrow(s: string): AmountJson {
   const res = parse(s);
   if (!res) {
@@ -245,6 +263,7 @@ export function parseOrThrow(s: string): AmountJson {
   return res;
 }
 
+
 /**
  * Convert the amount to a float.
  */
@@ -252,6 +271,7 @@ export function toFloat(a: AmountJson): number {
   return a.value + (a.fraction / fractionalBase);
 }
 
+
 /**
  * Convert a float to a Taler amount.
  * Loss of precision possible.
@@ -264,6 +284,7 @@ export function fromFloat(floatVal: number, currency: string) {
   };
 }
 
+
 /**
  * Convert to standard human-readable string representation that's
  * also used in JSON formats.
@@ -272,6 +293,10 @@ export function toString(a: AmountJson) {
   return `${a.currency}:${a.value + (a.fraction / fractionalBase)}`;
 }
 
+
+/**
+ * Check if the argument is a valid amount in string form.
+ */
 export function check(a: any) {
   if (typeof a !== "string") {
     return false;
diff --git a/src/i18n.tsx b/src/i18n.tsx
index dfd1528e3..ddf4fb768 100644
--- a/src/i18n.tsx
+++ b/src/i18n.tsx
@@ -26,24 +26,32 @@ import {strings} from "./i18n/strings";
 import * as jedLib from "jed";
 import * as React from "react";
 
-let lang: string;
-try {
-  lang = chrome.i18n.getUILanguage();
-  // Chrome gives e.g. "en-US", but Firefox gives us "en_US"
-  lang = lang.replace("_", "-");
-} catch (e) {
-  lang = "en";
-  console.warn("i18n default language not available");
+
+const jed = setupJed();
+
+
+/**
+ * Set up jed library for internationalization,
+ * based on browser language settings.
+ */
+function setupJed(): any {
+  let lang: string;
+  try {
+    lang = chrome.i18n.getUILanguage();
+    // Chrome gives e.g. "en-US", but Firefox gives us "en_US"
+    lang = lang.replace("_", "-");
+  } catch (e) {
+    lang = "en";
+    console.warn("i18n default language not available");
+  }
+
+  if (!strings[lang]) {
+    lang = "en-US";
+    console.log(`language ${lang} not found, defaulting to english`);
+  }
+  return new jedLib.Jed(strings[lang]);
 }
 
-if (!strings[lang]) {
-  lang = "en-US";
-  console.log(`language ${lang} not found, defaulting to english`);
-}
-
-const jed = new jedLib.Jed(strings[lang]);
-
-
 
 /**
  * Convert template strings to a msgid
diff --git a/src/talerTypes.ts b/src/talerTypes.ts
index 15e0009fd..f8fb72b93 100644
--- a/src/talerTypes.ts
+++ b/src/talerTypes.ts
@@ -896,9 +896,16 @@ export function isWireDetail(x: any): x is WireDetail {
  */
 @Checkable.Class({extra: true})
 export class Proposal {
+  /**
+   * Contract terms for the propoal.
+   */
   @Checkable.Value(() => ContractTerms)
   contract_terms: ContractTerms;
 
+  /**
+   * Signature over contract, made by the merchant.  The public key used for signing
+   * must be contract_terms.merchant_pub.
+   */
   @Checkable.String()
   sig: string;
 
diff --git a/src/wallet.ts b/src/wallet.ts
index 1d15722e3..8655c59ca 100644
--- a/src/wallet.ts
+++ b/src/wallet.ts
@@ -2754,7 +2754,7 @@ export class Wallet {
       return this.activeTipOperations[key];
     }
     const p = this.processTipImpl(tipToken);
-    this.activeTipOperations[key] = p
+    this.activeTipOperations[key] = p;
     try {
       return await p;
     } finally {
@@ -2892,7 +2892,7 @@ export class Wallet {
   async getTipStatus(tipToken: TipToken): Promise<TipStatus> {
     const tipId = tipToken.tip_id;
     const merchantDomain = new URI(tipToken.pickup_url).origin();
-    let tipRecord = await this.q().get(Stores.tips, [tipId, merchantDomain]);
+    const tipRecord = await this.q().get(Stores.tips, [tipId, merchantDomain]);
     const amount = Amounts.parseOrThrow(tipToken.amount);
     const exchangeUrl = tipToken.exchange_url;
     this.processTip(tipToken);
diff --git a/src/webex/compat.ts b/src/webex/compat.ts
index 30ffd4a81..65ddfab4a 100644
--- a/src/webex/compat.ts
+++ b/src/webex/compat.ts
@@ -15,9 +15,9 @@
  */
 
 /**
-* Compatibility helpers needed for browsers that don't implement
-* WebExtension APIs consistently.
-*/
+ * Compatibility helpers needed for browsers that don't implement
+ * WebExtension APIs consistently.
+ */
 
 export function isFirefox(): boolean {
     const rt = chrome.runtime as any;
diff --git a/src/webex/pages/confirm-contract.tsx b/src/webex/pages/confirm-contract.tsx
index f1e98f22b..41eebda8e 100644
--- a/src/webex/pages/confirm-contract.tsx
+++ b/src/webex/pages/confirm-contract.tsx
@@ -379,7 +379,8 @@ class ContractPrompt extends React.Component<ContractPromptProps, ContractPrompt
           {products}
           {(this.state.payStatus && this.state.payStatus.coinSelection)
             ? <i18n.Translate wrap="p">
-                The total price is <span>{amount} </span> (plus <span>{renderAmount(this.state.payStatus.coinSelection.totalFees)}</span> fees).
+                The total price is <span>{amount} </span>
+                (plus <span>{renderAmount(this.state.payStatus.coinSelection.totalFees)}</span> fees).
               </i18n.Translate>
             :
             <i18n.Translate wrap="p">The total price is <span>{amount}</span>.</i18n.Translate>
diff --git a/src/webex/pages/confirm-create-reserve.tsx b/src/webex/pages/confirm-create-reserve.tsx
index 5be6fe351..cef647163 100644
--- a/src/webex/pages/confirm-create-reserve.tsx
+++ b/src/webex/pages/confirm-create-reserve.tsx
@@ -340,7 +340,7 @@ class ExchangeSelection extends ImplicitStateComponent<ExchangeSelectionProps> {
             <button className="pure-button button-success" onClick={() => this.select(this.props.suggestedExchangeUrl)}>
               <i18n.Translate wrap="span">
               Select <strong>{this.props.suggestedExchangeUrl}</strong>
-              </i18n.Translate> 
+              </i18n.Translate>
             </button>
           </div>
         )}
diff --git a/src/webex/pages/tip.tsx b/src/webex/pages/tip.tsx
index 6fbb3005d..c13120c43 100644
--- a/src/webex/pages/tip.tsx
+++ b/src/webex/pages/tip.tsx
@@ -30,8 +30,8 @@ import * as i18n from "../../i18n";
 
 import {
   acceptTip,
-  getTipStatus,
   getReserveCreationInfo,
+  getTipStatus,
 } from "../wxApi";
 
 import {
diff --git a/src/webex/wxApi.ts b/src/webex/wxApi.ts
index 32788d37b..e5da642f1 100644
--- a/src/webex/wxApi.ts
+++ b/src/webex/wxApi.ts
@@ -72,6 +72,9 @@ export interface UpgradeResponse {
 }
 
 
+/**
+ * Error thrown when the function from the backend (via RPC) threw an error.
+ */
 export class WalletApiError extends Error {
   constructor(message: string, public detail: any) {
     super(message);
diff --git a/src/webex/wxBackend.ts b/src/webex/wxBackend.ts
index 0b4f0976e..b1aecbbdd 100644
--- a/src/webex/wxBackend.ts
+++ b/src/webex/wxBackend.ts
@@ -475,7 +475,10 @@ function waitMs(timeoutMs: number): Promise<void> {
 }
 
 
-function makeSyncWalletRedirect(url: string, tabId: number, oldUrl: string, params?: {[name: string]: string | undefined}): object {
+function makeSyncWalletRedirect(url: string,
+                                tabId: number,
+                                oldUrl: string,
+                                params?: {[name: string]: string | undefined}): object {
   const innerUrl = new URI(chrome.extension.getURL("/src/webex/pages/" + url));
   if (params) {
     for (const key in params) {
@@ -552,8 +555,8 @@ function handleHttpPayment(headerList: chrome.webRequest.HttpHeader[], url: stri
   if (fields.contract_url) {
     return makeSyncWalletRedirect("confirm-contract.html", tabId, url, {
       contractUrl: fields.contract_url,
-      sessionId: fields.session_id,
       resourceUrl: fields.resource_url,
+      sessionId: fields.session_id,
     });
   }