marcelmokos

const fullName = (
  {firstName = "", lastName = ""}          // we are providing default values
  : {firstName: string, lastName: string}  // type, can be inferenced
  = {}                                     // default value object for object argument
) => `${firstName} ${lastName}`;

marcelmokos

function add(a: number, b: number): number { return a + b };

const add = (a: number, b: number): number => a + b;

type Arithmetics = (a: number, b: number) => number;
// or
/*
interface  Arithmetics {
  (a: number, b: number): number;
}

marcelmokos

/**
 * A person object with name, age and sayName method.
 * @typedef {Object} Person 
 * @property {string} name The person's name.
 * @property {number} age The person's age.
 * @property {Function} sayName A function that alerts the person's name.
 */
const person = {
  name: 'Joe',
  age: 32,

marcelmokos

import React from "react";
import {inject, observer} from "mobx-react";
export class SubjectsPresenter extends React.Component {...}

export default inject(
  ({subjectStore, translator}, {subjectSelections, ...props}) => {
    const subjectOptions = subjectStore.getFilteredSubjects(subjectSelections);

    return {
      subjectOptions,

marcelmokos

// see types of prompts:
// https://github.com/enquirer/enquirer/tree/master/examples
//
module.exports = [
  {
    type: "input",
    name: "name",
    message: "What's the name of your package?"
  },
  {

marcelmokos

Calendar.defaultProps = {
  Wrapper: styled.div`
    display: flex;
    flex-direction: row;
  `,
  Column: styled.div`
    display: flex;
    flex-direction: column;
    margin: 0.5rem;
  `,

marcelmokos

import React from "react";
import ReactDOM from "react-dom";
import Calendar from "./components/Calendar";

const App = () => (
  <>
    <Calendar>
      {({ Wrapper, Column, Box, Item, headers }) => (
        <Wrapper>
          {headers.map((header, index) => (

marcelmokos

const FormattedNumber = ({ value, roundingFn = val => val }) => roundingFn(value);

//js
console.log(
  FormattedNumber({value: 5.6}) /* 5.6 */
); 

//jsx
<FormattedNumber value={5.6} /> /* 5.6 */
<FormattedNumber value={5.6} roundingFn={Math.floor} /> /* 5 */

marcelmokos

/*-------- Promise.then() syntax ---------*/

// when expect() is in Promise.then() method body
// we have to use callback function done()
it("test two inputs to have labels with same classes using Promise.then() ", (done) => {
  getInputsLabelElement(input1).then((label1) => {
    getInputsLabelElement(input2).then((label2) => {
      label1.getAttribute("class").then((label1Classes) => {
        label2.getAttribute("class").then((label2Classes) => {
          expect(label1Classes).toBe(label2Classes);

marcelmokos