MongoDB Connection
2 likes • Oct 15, 2022
JavaScript
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const quickSort = arr => {const a = [...arr];if (a.length < 2) return a;const pivotIndex = Math.floor(arr.length / 2);const pivot = a[pivotIndex];const [lo, hi] = a.reduce((acc, val, i) => {if (val < pivot || (val === pivot && i != pivotIndex)) {acc[0].push(val);} else if (val > pivot) {acc[1].push(val);}return acc;},[[], []]);return [...quickSort(lo), pivot, ...quickSort(hi)];};quickSort([1, 6, 1, 5, 3, 2, 1, 4]); // [1, 1, 1, 2, 3, 4, 5, 6]
const formatDuration = ms => {if (ms < 0) ms = -ms;const time = {day: Math.floor(ms / 86400000),hour: Math.floor(ms / 3600000) % 24,minute: Math.floor(ms / 60000) % 60,second: Math.floor(ms / 1000) % 60,millisecond: Math.floor(ms) % 1000};return Object.entries(time).filter(val => val[1] !== 0).map(([key, val]) => `${val} ${key}${val !== 1 ? 's' : ''}`).join(', ');};formatDuration(1001); // '1 second, 1 millisecond'formatDuration(34325055574); // '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'
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
class SequentialQueue{ //if you want it to go backwards, too badnext(){return this.i++;}constructor(start = 0){this.i = start;}}const que = new SequentialQueue(0);for(let i = 0; i < 10; i++){console.log(que.next());}
const arithmeticProgression = (n, lim) =>Array.from({ length: Math.ceil(lim / n) }, (_, i) => (i + 1) * n );arithmeticProgression(5, 25); // [5, 10, 15, 20, 25]
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();}}