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const luhnCheck = num => {let arr = (num + '').split('').reverse().map(x => parseInt(x));let lastDigit = arr.splice(0, 1)[0];let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val *= 2) > 9 ? val - 9 : val)),0);sum += lastDigit;return sum % 10 === 0;};luhnCheck('4485275742308327'); // trueluhnCheck(6011329933655299); // trueluhnCheck(123456789); // false
const geometricProgression = (end, start = 1, step = 2) =>Array.from({length: Math.floor(Math.log(end / start) / Math.log(step)) + 1,}).map((_, i) => start * step ** i);geometricProgression(256); // [1, 2, 4, 8, 16, 32, 64, 128, 256]geometricProgression(256, 3); // [3, 6, 12, 24, 48, 96, 192]geometricProgression(256, 1, 4); // [1, 4, 16, 64, 256]
class Graph {constructor(directed = true) {this.directed = directed;this.nodes = [];this.edges = new Map();}addNode(key, value = key) {this.nodes.push({ key, value });}addEdge(a, b, weight) {this.edges.set(JSON.stringify([a, b]), { a, b, weight });if (!this.directed)this.edges.set(JSON.stringify([b, a]), { a: b, b: a, weight });}removeNode(key) {this.nodes = this.nodes.filter(n => n.key !== key);[...this.edges.values()].forEach(({ a, b }) => {if (a === key || b === key) this.edges.delete(JSON.stringify([a, b]));});}removeEdge(a, b) {this.edges.delete(JSON.stringify([a, b]));if (!this.directed) this.edges.delete(JSON.stringify([b, a]));}findNode(key) {return this.nodes.find(x => x.key === key);}hasEdge(a, b) {return this.edges.has(JSON.stringify([a, b]));}setEdgeWeight(a, b, weight) {this.edges.set(JSON.stringify([a, b]), { a, b, weight });if (!this.directed)this.edges.set(JSON.stringify([b, a]), { a: b, b: a, weight });}getEdgeWeight(a, b) {return this.edges.get(JSON.stringify([a, b])).weight;}adjacent(key) {return [...this.edges.values()].reduce((acc, { a, b }) => {if (a === key) acc.push(b);return acc;}, []);}indegree(key) {return [...this.edges.values()].reduce((acc, { a, b }) => {if (b === key) acc++;return acc;}, 0);}outdegree(key) {return [...this.edges.values()].reduce((acc, { a, b }) => {if (a === key) acc++;return acc;}, 0);}}const g = new Graph();g.addNode('a');g.addNode('b');g.addNode('c');g.addNode('d');g.addEdge('a', 'c');g.addEdge('b', 'c');g.addEdge('c', 'b');g.addEdge('d', 'a');g.nodes.map(x => x.value); // ['a', 'b', 'c', 'd'][...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);// ['a => c', 'b => c', 'c => b', 'd => a']g.adjacent('c'); // ['b']g.indegree('c'); // 2g.outdegree('c'); // 1g.hasEdge('d', 'a'); // trueg.hasEdge('a', 'd'); // falseg.removeEdge('c', 'b');[...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);// ['a => c', 'b => c', 'd => a']g.removeNode('c');g.nodes.map(x => x.value); // ['a', 'b', 'd'][...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);// ['d => a']g.setEdgeWeight('d', 'a', 5);g.getEdgeWeight('d', 'a'); // 5
//Retries maxRetries number of times, meaning that if you have 0, then it'll run the function once.async function retryPromise(promiseFn, maxRetries = 3, delayOffset = 0, delayRandomRange = 0) {return new Promise((resolve, reject) => {promiseFn().then(resolve, (error) => { //On errorif (maxRetries <= 0) {return reject(error);} else {if(delayRandomRange * Math.random() + delayOffset < 1.0){return retryPromise(promiseFn, maxRetries - 1, delayOffset, delayRandomRange).then(resolve, reject);}else{return new Promise((resolveTwo, rejectTwo) => {setTimeout(() => {return retryPromise(promiseFn, maxRetries - 1, delayOffset, delayRandomRange).then(resolveTwo, rejectTwo);}, delayRandomRange * Math.random() + delayOffset);}).then(resolve, reject);}}});});}//Tests for that function.//Returns a function that will fail numTimes times, then will return aValuefunction functionThatReturnsAFunctionThatFailsACoupleTimes(numTimes, aValue){return async function(){if(numTimes == 0){return aValue;}numTimes--;throw false;};}const SMALL_NUMBER = 10;function testTest(failNumberOfTimes){let functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(failNumberOfTimes, true);//Test my testfor(let i = 0; i < (failNumberOfTimes * 2); ++i){function evalTest(val){let testTestFailedReason = "";if(val === undefined){testTestFailedReason = "Test test returned undefined for some reason.";}if((i + 1) > failNumberOfTimes){if(val === true){//We're good}else{testTestFailedReason = "Test test didn't return true when it should have.";}}else{if(val === false){//We're good}else{testTestFailedReason = "Test test didn't return false when it should have.";}}testTestFailedReason = testTestFailedReason || "Test test passed test case";console.log(testTestFailedReason, "at index", i, "where the function returned", val);}functionThatFailsACoupleTimes().then(evalTest, evalTest)};}testTest(SMALL_NUMBER);let testCaseCounter = 1;const throwsNoError = [(val)=>{if(val == true){console.log("Passed test case " + (testCaseCounter++));}else{console.error("Unexpected return value", val);}},()=>{console.error("It wasn't supposed to fail!")}]const throwsError = [(val)=>{console.error("It wasn't supposed to succeed!", val);},(val)=>{if(val == false){console.log("Passed test case " + (testCaseCounter++));}else{console.error("Unexpected return value", val);}}];//Runs SMALL_NUMBER times, because SMALL_NUMBER - 1 is the number of retries after the first onelet functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 1).then(...throwsNoError)functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);//Runs SMALL_NUMBER - 1 times, because SMALL_NUMBER - 2 is the number of retries after the first oneretryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 2).then(...throwsError)//Testing the delay. You'll have to wait a bit too.functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);//Runs SMALL_NUMBER times, because SMALL_NUMBER - 1 is the number of retries after the first oneretryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 1, 500, 500).then(...throwsNoError)functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);//Runs SMALL_NUMBER - 1 times, because SMALL_NUMBER - 2 is the number of retries after the first oneretryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 2, 500, 500).then(...throwsError)
class Timer{start(){this.startTime = Date.now();}stop(){const dt = Date.now() - this.startTime;console.log(dt);return dt;}getExecTime(fun, asynchronous){return asynchronous ? this.getAsyncExecTime(fun) : this.getSyncExecTime(fun);}getSyncExecTime(fun){this.start();fun();return this.stop();}async getAsyncExecTime(fun){this.start();await fun();return this.stop();}static average(fun, numTimes, asynchronous = false){const times = [];const promises = [];let timer = new Timer();if(asynchronous){for(let i = 0; i < numTimes; i++){timer.getAsyncExecTime(fun);}}else{for(let i = 0; i < numTimes; i++){timer.getSyncExecTime(fun);}}return (times => times.reduce(((sum, acc) => sume + acc), 0) / times.length);}static async timeAsync(fun, numTimes){if(numTimes <= 1) return new Timer().getAsyncExecTime(fun);const promises = [];let timer = new Timer(true);for(let i = 0; i < numTimes; i++){promises.push(fun().catch((e)=>{}));}try{await Promise.all(promises).catch((e)=>{});}catch(e){//do absolutely nothing}return timer.stop();}constructor(start = false){if(start) this.start();}}
"use strict";const nodemailer = require("nodemailer");// async..await is not allowed in global scope, must use a wrapperasync function main() {// Generate test SMTP service account from ethereal.email// Only needed if you don't have a real mail account for testinglet testAccount = await nodemailer.createTestAccount();// create reusable transporter object using the default SMTP transportlet transporter = nodemailer.createTransport({host: "smtp.ethereal.email",port: 587,secure: false, // true for 465, false for other portsauth: {user: testAccount.user, // generated ethereal userpass: testAccount.pass, // generated ethereal password},});// send mail with defined transport objectlet info = await transporter.sendMail({subject: "Hello ✔", // Subject linetext: "Hello world?", // plain text bodyhtml: "<b>Hello world?</b>", // html body});console.log("Message sent: %s", info.messageId);// Message sent: <[email protected]>// Preview only available when sending through an Ethereal accountconsole.log("Preview URL: %s", nodemailer.getTestMessageUrl(info));// Preview URL: https://ethereal.email/message/WaQKMgKddxQDoou...}main().catch(console.error);