Complete Course

JavaScript for QAs

The language your tests are written in, from the ground up: types, variables, operators, functions, conditionals, loops, iterators, destructuring, and async/await. Every topic is taught in plain JavaScript first, then applied to real test code.

~5 hours of content

View Lessons

Course Content

16 comprehensive lessons covering everything you need to know

Introduction

Course Structure

Learn how the course is organized and make the most of the content.

Introduction

Prerequisites

Systems and knowledge required to complete the course. No Docker, and no programming background needed.

Introduction

How you will practice

Your repository starts empty. You write the code, run it with Node.js, commit it, and push it to your own fork.

Lesson

Lesson 1

Fork, clone, and run your first file

Fork the empty project, clone it, write your first JavaScript file, run it with Node.js, and push your first commit.

JavaScript building blocks

Lesson

Lesson 2

Data types

The primitives (undefined, null, Boolean, Number, String) and the structural types (Array, Object, Function) every test is built out of.

Lesson

Lesson 3

Variables

var, let, and const, starting with primitives and then with arrays and objects, where const stops meaning what you expect.

Lesson

Lesson 4

Operators

Assignment, maths, and logic, including the == versus === difference that decides whether your assertion is telling the truth.

Lesson

Lesson 5

Strings: concatenation and template literals

Joining text with + and with backticks, and writing test names and failure messages that say which case failed.

Lesson

Lesson 6

Data transformation

toString, split, reverse, join, replace, replaceAll, slice, trim, toLowerCase, and toUpperCase, applied to text read off a page.

Structure and flow

Lesson

Lesson 7

Functions

Declarations, arrow functions, pure versus impure, and higher-order functions, which is what every it() and beforeEach() really is.

Lesson

Lesson 8

Modules: export and import

Split your code into files, export what you wrote, and import it somewhere else, which is how helpers and test data get shared.

Lesson

Lesson 9

Conditionals

if, else if, else, and the ternary, plus why a conditional inside a test is usually a warning sign.

Lesson

Lesson 10

Loops

for, for...of, and while, and the difference between looping inside one test and generating many tests.

Lesson

Lesson 11

Array iterators

forEach, map, filter, find, some, and every, and how one array of test data turns into a whole set of tests.

Working with data

Lesson

Lesson 12

Destructuring

Pulling values out of arrays and objects by position and by name, the way you unpack an API response body.

Lesson

Lesson 13

Rest and spread

The same three dots doing two opposite jobs, and how they build a test payload that differs from the default by one field.

Lesson

Lesson 14

JSON

JSON.parse and JSON.stringify, what JSON cannot hold, and why a fixture file loaded once can break the test that runs after it.

Asynchronous JavaScript and paradigms

Lesson

Lesson 15

Promises and async/await

What a promise is, what await does, and why an API call without await passes a test that never actually ran.

Lesson

Lesson 16

Object-oriented versus functional JavaScript

The same helper written as a class and as plain functions, and why the simpler one is the better default for test code.

Bonus & Conclusion

Bonus

Bonus: JavaScript in the browser console

querySelector, querySelectorAll, and the handful of DevTools console commands that make finding a selector a ten-second job.

Bonus

Bonus: useful libraries for testers

Faker.js for test data and Lodash for the array and object work you would otherwise hand-write, plus when not to reach for them.

Bonus

Bonus: a first look at TypeScript

TypeScript as syntax sugar over the JavaScript you just learned: types on variables, parameters, and return values, and what it catches.

Bonus

Bonus: coding questions in QA interviews

The exercises QA candidates are actually given, all solvable with this course's content, and what the interviewer is really marking.

Conclusion

Congratulations!

You've completed the JavaScript for QAs course!