Frontend

Da li ste ikada imali iskustvo rada bez analitičara, kada ste morali sami da shvatite zadatak?

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Šta je WeakMap?

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Kako shvatiš šta je render u React-u? Zbog čega može doći do toga?

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import React, { useState, useEffect, useRef, useContext, useReducer, useMemo } from 'react'; export default Effects = () => { const [count, setCount] = useState(0); useLayoutEffect(() => console.log("сваки рендер 1")); console.log("сваки рендер 2"); useEffect(() => console.log("сваки рендер 3")); return ( <> <button onClick={() => setCount((prevProps) => ++prevProps)}> Увеличи </button> </> ) }

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Koje postavke imaju kolačići (httpOnly, secure, expires, domain, path)?

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const { foo: bar, bar: foo } = { foo: 1, bar: 2 } console.log(bar) // console.log(foo) //

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const obj = [{ value: 1, elems: [ { value: 2, elems: [ { value: 3 }, { value: 6 }, ... ] }, { value: 4, elems: [ { value: 5, elems: [ { value: 6 }, ... ]} ] } ] }] ------------- setTimeout(() => { console.log(1); }, 0); const p = new Promise(resolve => { console.log(2); resolve(); }); p.then(() => { console.log(3) }).then(() => { console.log(4); }); console.log(5);

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const createCounter = () => {

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Ispričaj mi o Event Loop-u: kako radi, šta su mikro zadaci i makro zadaci?

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const { foo: bar, bar: foo } = { foo: 1, bar: 2 }; //foo //bar setTimeout(() => { console.log("timeOut"); }, 0); console.log(1); new Promise((resolve) => { console.log("Promise"); setTimeout(() => { console.log("timeOut2"); resolve(); }, 0); }) .then(() => { console.log("then1"); }) .then(() => { console.log("then2"); }); console.log(4); setTimeout(() => { console.log("timeOut3"); }, 0);

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Kako React poredi props? Kako funkcioniše površinsko poređenje?

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import { useState, useRef, useEffect } from "react"; const useDebugRender = ({props}) => { const prevProp = useRef(props) useEffect(() => { }, []) } const ParentComponent = () => { const [random, setRandom] = useState(0); // Se transmite como Prop al componente hijo const [text, setText] = useState(""); // Se transmite como Prop al componente hijo const createRandom = () => setRandom(Math.floor(Math.random() * 100)); const onTextChange = (e) => setText(e.target.value); const [count, setCount] = useState(0); const incrementCount = () => setCount((prev) => prev + 1); // Esta función se transmite como Prop al componente hijo return ( <> <Count: {count} /> <input type="text" onChange={onTextChange} /> <button onClick={createRandom}>Generar aleatorio</button> <div> <ChildComponent random={random} text={text} incrementCount={incrementCount} /> </div> </> ); }; export default ParentComponent;

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Зашто debounce, а не throttle за претрагу?

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Чему служи useRef? Које су његове примене?

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Ako roditeljski komponent prosledi novi niz kao props, da li ćeš videti nove podatke na ekranu ili stare? Zašto?

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Tipiziraj funkciju getParam tako da TypeScript sam istakne prisustvo svojstava u objektu. Napravi tipizaciju tako da ne bude moguće prosleđivati nizove.

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const submit = useCallback((el) => () => { log(el); }, []); arr.map(el => <button onClick={submit(el)} />) arr.map(el => <SomeComp key={} onClick={() => submit(el)} />) const param = useMemo(() => ({c: a + b}), [a,b]) return <Child value={param} /> Child = React.memo(() => {})

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Koja je razlika između await p1, await p2 i Promise.all([p1, p2])?

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const Effects = () => { const [count, setCount] = useState(0); useLayoutEffect(() => console.log("svaki render 1")); console.log("svaki render 2"); useEffect(() => console.log("svaki render 3")); return ( <> {count} <button onClick={() => setCount((prevProps) => ++prevProps)}> Povečaj </button> </> ); }; export default Effects; // 1 render: // Po kliku: const Effects = () => { const [count, setCount] = useState(0); const [number, setNumber] = useState(0); useEffect(() => { console.log(count); return () => { console.log(count); }; }); return ( <> {count} <button onClick={() => setCount((prevProps) => ++prevProps)}> Povečaj </button> </> ); }; export default Effects; // 1 render: // 2 1 3 // Po kliku: // 2 1 3 // null: // 2 1 3 // // 1: 1, 0 // +: 1, 2 // ++: 2, 2

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let obj = { a: 1 }; let array = [obj]; obj = null; console.log(obj); // console.log(array); //

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