avaScript Interview: nsider Tricks You Should Know

Four advanced JavaScript techniques could surprise you in your next interview. Let’s keep it short and sweet with just the key points and code examples.

1. Top-Level Await

// Fetching data at the module level
const response = await fetch('https://api.example.com/data');
const data = await response.json();

export default data;

Key Point: Simplifies async operations in modules.

Example: Imagine you need to fetch configuration settings from an API before initializing your app. Top-Level Await makes this straightforward without wrapping everything in async functions.

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2. Temporal API (Stage 3 Proposal)

import { Temporal } from '@js-temporal/polyfill';

// Get current date and time
const now = Temporal.Now.plainDateTimeISO();
console.log(now.toString()); // 2024-08-12T10:00:00

Key Point: Better handling of dates/times than Date object.

Example: Working on a global app? The Temporal API allows you to accurately handle time zones, avoiding the pitfalls of the Date object.

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3. Pattern Matching (Stage 3 Proposal)

const value = { x: 1, y: 2 };
const result = match (value) {
  {x: 1, y: 2} => 'Point at (1, 2)',
  {x, y} if (x > y) => 'X is greater',
  _ => 'Unknown pattern'
};
console.log(result);

Key Point: Powerful alternative to switch statements.

Example: Simplify complex conditional logic in data processing by matching patterns directly, reducing the need for nested if-else statements.

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4. Records and Tuples (Stage 2 Proposal)

const record = #{ x: 1, y: 2 };
const tuple = #[1, 2, 3];

console.log(record.x); // 1
console.log(tuple[0]); // 1

Key Point: Immutable data structures for safer code.

Example: Use Records and Tuples to ensure that critical data structures remain unchanged throughout your application, preventing unintended mutations.

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