return array head
0 likes • Nov 19, 2022
JavaScript
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const deepMerge = (a, b, fn) =>[...new Set([...Object.keys(a), ...Object.keys(b)])].reduce((acc, key) => ({ ...acc, [key]: fn(key, a[key], b[key]) }),{});deepMerge({ a: true, b: { c: [1, 2, 3] } },{ a: false, b: { d: [1, 2, 3] } },(key, a, b) => (key === 'a' ? a && b : Object.assign({}, a, b)));// { a: false, b: { c: [ 1, 2, 3 ], d: [ 1, 2, 3 ] } }
const getTimezone = () => Intl.DateTimeFormat().resolvedOptions().timeZone;// ExamplegetTimezone();
const reverse = str => str.split('').reverse().join('');reverse('hello world');// Result: 'dlrow olleh'
// Vanilla JS Solution:var app = document.getElementById('app');var typewriter = new Typewriter(app, { loop: true });typewriter.typeString("I'm John and I'm a super cool web developer").pauseFor(3000).deleteChars(13) // "web developer" = 13 characters.typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!".start();// React Solution:import Typewriter from 'typewriter-effect';<Typewriteroptions={{ loop: true }}onInit={typewriter => {typewriter.typeString("I'm John and I'm a super cool web developer").pauseFor(3000).deleteChars(13) // "web developer" = 13 characters.typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!".start();}}/>
const kNearestNeighbors = (data, labels, point, k = 3) => {const kNearest = data.map((el, i) => ({dist: Math.hypot(...Object.keys(el).map(key => point[key] - el[key])),label: labels[i]})).sort((a, b) => a.dist - b.dist).slice(0, k);return kNearest.reduce((acc, { label }, i) => {acc.classCounts[label] =Object.keys(acc.classCounts).indexOf(label) !== -1? acc.classCounts[label] + 1: 1;if (acc.classCounts[label] > acc.topClassCount) {acc.topClassCount = acc.classCounts[label];acc.topClass = label;}return acc;},{classCounts: {},topClass: kNearest[0].label,topClassCount: 0}).topClass;};const data = [[0, 0], [0, 1], [1, 3], [2, 0]];const labels = [0, 1, 1, 0];kNearestNeighbors(data, labels, [1, 2], 2); // 1kNearestNeighbors(data, labels, [1, 0], 2); // 0
function Clock(props) {return (<div><h1>Hello, world!</h1><h2>It is {props.date.toLocaleTimeString()}.</h2></div>);}function tick() {ReactDOM.render(<Clock date={new Date()} />,document.getElementById('root'));}setInterval(tick, 1000);