jfhector

react-intl: When to use defineMessage and why

It's generally better to define messages inline as arguments of intl.formatMessage(...). (Because linting only works that way.)

But this pageH1Message needs to be used in two places. So we assign that message to a variable using defineMessage, then use that message in two places.

(If we had defined the same message twice inline, we'd have ended up with two identical messages in the translation file, with makes managing translation harder).

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import express from 'express';
import cors from 'cors';

const PORT = 7890;

const server = express();
server.use(cors())

server.get('/me', (req, res) => {
  console.log("A request was just made");

jfhector

Implementing simple Monads

From the book "Mastering Functional Programming"

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Lenses in JS

From "Mastering JavaScript Functional Programming"

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The tower of Hanoi problem solved using recursion

More info: https://en.wikipedia.org/wiki/Tower_of_Hanoi#Recursive_solution

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Getting a value from a request header, and using that value to show a banner – both Server-Side and Client-Side rendered

How this works

### In the renderApp Express route handler

1. We look at the value of a request header with the visitor's location country.
2. We pass that value to <App visitorLocationCountry={visitorLocationCountry} /> (i.e. App being called when rendered to string on the server).
3. We generate a HTML meta tag string using that visitor code, and put that in the head of the generated index.html document

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/* eslint-disable @typescript-eslint/no-empty-function */

import { assertHasProperty } from '../';

test(`Given it's called with an object that has the specified property
  And that property does NOT hold 'undefined'
  Then it does NOT throw`, () => {
  expect(() => {
    assertHasProperty('nameOfThePropertyImLookingFor', {
      nameOfThePropertyImLookingFor: {},

jfhector

Feature: wrapInAsyncTryCatch

Scenario: The function returned by wrapInAsyncTryCatch calls the function provided to wrapInAsyncTryCatch with the same arguments
  Given wrapInAsyncTryCatch is called with an asynchronous function that does not throw
  When the function returned by wrapInAsyncTryCatch is called with some arguments
  Then the function provided to wrapInAsyncTryCatch gets called with the same arguments
  And the function returned by wrapInAsyncTryCatch returns the same thing as the provided function

Scenario: It catches any error that the provided function throws
  Given wrapInAsyncTryCatch is called with an asynchronous function that throws when called with some arguments

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Feature: wrapInSynchronousTryCatch

Scenario: The function returned by wrapInSynchronousTryCatch calls the function provided to wrapInSynchronousTryCatch with the same arguments
  Given wrapInSynchronousTryCatch is called with a synchronous function that does not throw
  When the function returned by wrapInSynchronousTryCatch is called with some arguments
  Then the function provided to wrapInSynchronousTryCatch gets called with the same arguments
  And the function returned by wrapInSynchronousTryCatch returns the same thing as the provided function

Scenario: It catches any error that the provided function throws
  Given wrapInSynchronousTryCatch is called with a synchronous function that throws when called with some arguments

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