Blog
JavaScript for people who write tests
Short articles that link into the tutorial and interview bank. Written for QA, SDET, and anyone tired of React-first JS blogs.
2026-09-14 · 6 min
The JavaScript questions QA and SDET interviews actually ask
A tester-first list of JS interview topics: closures, the event loop, fetch, JSON, and assertions — with links into JS Practice.
2026-09-14 · 7 min
Promises vs async/await — explained for people who write tests
When to await, when Promise.all is faster, and the forEach(async) trap that shows up in Playwright helpers.
2026-09-14 · 6 min
The event loop, in the language of flakes
Why a 0ms timeout is not instant, why microtasks beat timers, and how that shows up in UI tests.
2026-09-14 · 5 min
Closures: the loop bug every tester meets twice
Why var in a for loop shares one i, how let fixes it, and how Playwright fixtures are closures too.
2026-09-14 · 6 min
JSON.stringify gotchas that break API assertions
What JSON drops, why Dates come back as strings, and how to pretty-print a 502 HTML page in a failure.
2026-09-14 · 4 min
?? vs || — why a price of 0 vanished
Nullish coalescing only fills in null and undefined. Logical or treats 0 and empty string as missing.
2026-09-14 · 6 min
this in JavaScript, without the mythology
Call site rules, arrows, bind, and the extracted-method bug that still shows up in page objects.
2026-09-14 · 7 min
JavaScript you must know before Playwright feels easy
Promises, locators vs arrays, map/filter on API bodies, and why sleep is how flakes are born.
2026-09-14 · 4 min
=== vs == and the assertion that passed for the wrong reason
Why 5 == "5" is a landmine in test helpers, and how Object.is treats NaN.
2026-09-14 · 8 min
A 30-day JavaScript roadmap for QA engineers
What to read and practice each week if you already test software and need JS for interviews and Playwright.