Which clause is used to rename a column or table in a SQL query result? Advanced SQL DeveloperEasy Try Now
Which SQL keyword prevents duplicate rows when combining results from two SELECT statements? Advanced SQL DeveloperEasy Try Now
What is the difference between `Array.prototype.reduceRight()` and `reduce()`? JavaScript ProfessionalMedium Try Now
What is the output of the following? “`js class EventEmitter { #handlers = {}; on(event, handler) { (this.#handlers[event] ??= []).push(handler); } emit(event, data) { this.#handlers[event]?.forEach(h => h(data)); } } const ee = new EventEmitter(); ee.on(‘test’, v => console.log(v * 2)); ee.emit(‘test’, 5); ee.emit(‘missing’, 5); “` JavaScript ProfessionalMedium Try Now
What is `Intl.Collator` used for and why is string comparison with `localeCompare()` important? JavaScript ProfessionalMedium Try Now
What is the output of the following? “`js async function* generate() { for (const n of [1, 2, 3]) { yield await Promise.resolve(n * 10); } } (async () => { const results = []; for await (const val of generate()) { results.push(val); } console.log(results); })(); “` JavaScript ProfessionalMedium Try Now
What is the purpose of `Object.defineProperty()` and when must you use it instead of direct assignment? JavaScript ProfessionalMedium Try Now
What is the output of the following? “`js const handler = { apply(target, thisArg, args) { return target.apply(thisArg, args) * 2; } }; const double = new Proxy(x => x + 1, handler); console.log(double(5)); “` JavaScript ProfessionalMedium Try Now
What is the output of the following? “`js let resolve; const p = new Promise(r => { resolve = r; }); p.then(v => console.log(‘resolved:’, v)); resolve(42); console.log(‘sync done’); “` JavaScript ProfessionalMedium Try Now
What is the difference between `Array.prototype.copyWithin()` and `Array.prototype.fill()`? JavaScript ProfessionalMedium Try Now
What is the output of the following? “`js function foo(a, b = a * 2, c = a + b) { return [a, b, c]; } console.log(foo(3)); “` JavaScript ProfessionalMedium Try Now
What is the `Temporal` proposal in JavaScript and what problem does it solve? JavaScript ProfessionalMedium Try Now
What is the output of the following? “`js const obj = {}; obj.a = 1; Object.defineProperty(obj, ‘b’, {value: 2, enumerable: false}); const copy = {…obj}; console.log(copy); “` JavaScript ProfessionalMedium Try Now
What is `WeakSet` in JavaScript and how does it differ from `Set`? JavaScript ProfessionalMedium Try Now
