JavaScript for frontend exams

Frontend JS is language + browser

Mixed frontend exams blend core JavaScript with DOM and browser APIs. You need language precision (===, falsy values, closures) and environment knowledge (events, fetch, localStorage). Studying only framework APIs leaves gaps.

When a question mentions the DOM or network, ask whether the answer is about language semantics or browser behavior — fetch’s non-rejection on HTTP 404 is a classic browser-API detail.

Language topics worth automatic recall

Prefer === to avoid coercion surprises. Know falsy values: false, 0, "", null, undefined, NaN. const prevents rebinding, not mutation. Array methods: map returns a new array, filter subsets, forEach returns undefined.

Async: promises and async/await; always handle failures. Closures: inner functions remember outer bindings. Spread vs rest use the same syntax in opposite directions. Hoisting: function declarations hoist fully; let/const exist in a temporal dead zone until initialized.

Browser and DOM topics

Event bubbling goes child to parent; capturing is the reverse. localStorage persists until cleared; sessionStorage lasts for the tab session; both store strings. JSON.parse is for JSON text — never use eval for untrusted input.

These details appear in the Frontend track and in Preparation tips under JavaScript. Drill them with timed quizzes so you do not burn minutes re-deriving basics during a real exam.

Practice suggestion

Use Frontend Beginner/Intermediate for mixed JS + browser items, and lean on the Preparation JavaScript category between sessions. If async questions are weak, do a short focused block: promise states, await errors, and fetch + response.ok checks.