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const compactObject = val => {const data = Array.isArray(val) ? val.filter(Boolean) : val;return Object.keys(data).reduce((acc, key) => {const value = data[key];if (Boolean(value))acc[key] = typeof value === 'object' ? compactObject(value) : value;return acc;},Array.isArray(val) ? [] : {});};const obj = {a: null,b: false,c: true,d: 0,e: 1,f: '',g: 'a',h: [null, false, '', true, 1, 'a'],i: { j: 0, k: false, l: 'a' }};compactObject(obj);// { c: true, e: 1, g: 'a', h: [ true, 1, 'a' ], i: { l: 'a' } }
import React, { useState } from 'react' import Welcome from '../components/Welcome' function About() { const [showWelcome, setShowWelcome] = useState(false) return ( <div> {showWelcome ? <Welcome /> : null} </div> <div> {showWelcome && <Welcome /> } </div> ) } export default App
var invertTree = function(root) {const reverseNode = node => {if (node == null) {return null}reverseNode(node.left);reverseNode(node.right);let holdLeft = node.left;node.left = node.right;node.right = holdLeft;return node;}return reverseNode(root);};
function formatDate(date) {return date.toLocaleDateString();}function Comment(props) {return (<div className="Comment"><div className="UserInfo"><imgclassName="Avatar"src={props.author.avatarUrl}alt={props.author.name}/><div className="UserInfo-name">{props.author.name}</div></div><div className="Comment-text">{props.text}</div><div className="Comment-date">{formatDate(props.date)}</div></div>);}const comment = {date: new Date(),text: 'I hope you enjoy learning React!',author: {name: 'Hello Kitty',avatarUrl: 'https://placekitten.com/g/64/64',},};ReactDOM.render(<Commentdate={comment.date}text={comment.text}author={comment.author}/>,document.getElementById('root'));
const shuffle = ([...arr]) => {let m = arr.length;while (m) {const i = Math.floor(Math.random() * m--);[arr[m], arr[i]] = [arr[i], arr[m]];}return arr;};const foo = [1, 2, 3];shuffle(foo); // [2, 3, 1], foo = [1, 2, 3]
//QM Helper by Leif Messinger//Groups numbers by number of bits and shows their binary representations.//To be used on x.comconst minterms = prompt("Enter your minterms separated by commas").split(",").map(x => parseInt(x.trim()));const maxNumBits = minterms.reduce(function(a, b) {return Math.max(a, Math.log2(b));});const bitGroups = [];for(let i = 0; i < maxNumBits; ++i){bitGroups.push([]);}for(const minterm of minterms){let outputString = (minterm+" ");//Count the bitslet count = 0;for (var i = maxNumBits; i >= 0; --i) {if((minterm >> i) & 1){++count;outputString += "1";}else{outputString += "0";}}bitGroups[count].push(outputString);}document.body.textContent = "";document.body.style.setProperty("white-space", "pre");for(const group of bitGroups){for(const outputString of group){document.body.textContent += outputString + "\r\n";}}