Timer
0 likes • Feb 5, 2021
JavaScript
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if (process.env.NODE_ENV === "production") {app.use(express.static("client/build"));app.get("*", (req, res) => {res.sendFile(path.resolve(__dirname, "client", "build", "index.html"));});}
const nums = [1, 2, 3];const strs = Array.from('est');nums.push(6);nums.push(4, 9);strs.unshift('t');nums.length; // 6nums[nums.length - 1]; // 9strs[0]; // 't'strs[2]; // 's'nums.slice(1, 3); // [2, 3]nums.map(n => n * 2); // [2, 4, 6, 12, 8, 18]nums.filter(n => n % 2 === 0); // [2, 6, 4]nums.reduce((a, n) => a + n, 0); // 25strs.reverse(); // ['t', 's', 'e', 't']strs.join(''); // 'test'const nums = new Set([1, 2, 3]);nums.add(4);nums.add(1);nums.add(5);nums.add(4);nums.size; // 5nums.has(4); // truenums.delete(4);nums.has(4); // false[...nums]; // [1, 2, 3, 5]nums.clear();nums.size; // 0const items = new Map([[1, { name: 'John' }],[2, { name: 'Mary' }]]);items.set(4, { name: 'Alan' });items.set(2, { name: 'Jeff' });items.size; // 3items.has(4); // trueitems.get(2); // { name: 'Jeff' }items.delete(2);items.size; // 2[...items.keys()]; // [1, 4][...items.values()]; // [{ name: 'John' }, { name: 'Alan' }]items.clear();items.size; // 0
class LinkedList {constructor() {this.nodes = [];}get size() {return this.nodes.length;}get head() {return this.size ? this.nodes[0] : null;}get tail() {return this.size ? this.nodes[this.size - 1] : null;}insertAt(index, value) {const previousNode = this.nodes[index - 1] || null;const nextNode = this.nodes[index] || null;const node = { value, next: nextNode };if (previousNode) previousNode.next = node;this.nodes.splice(index, 0, node);}insertFirst(value) {this.insertAt(0, value);}insertLast(value) {this.insertAt(this.size, value);}getAt(index) {return this.nodes[index];}removeAt(index) {const previousNode = this.nodes[index - 1];const nextNode = this.nodes[index + 1] || null;if (previousNode) previousNode.next = nextNode;return this.nodes.splice(index, 1);}clear() {this.nodes = [];}reverse() {this.nodes = this.nodes.reduce((acc, { value }) => [{ value, next: acc[0] || null }, ...acc],[]);}*[Symbol.iterator]() {yield* this.nodes;}}const list = new LinkedList();list.insertFirst(1);list.insertFirst(2);list.insertFirst(3);list.insertLast(4);list.insertAt(3, 5);list.size; // 5list.head.value; // 3list.head.next.value; // 2list.tail.value; // 4[...list.map(e => e.value)]; // [3, 2, 1, 5, 4]list.removeAt(1); // 2list.getAt(1).value; // 1list.head.next.value; // 1[...list.map(e => e.value)]; // [3, 1, 5, 4]list.reverse();[...list.map(e => e.value)]; // [4, 5, 1, 3]list.clear();list.size; // 0
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
var arr = [{"success": true,"data": [{"id": "ipi_1KrrbvDOiB2klwsKhuqUWqt1","object": "issuing.transaction","amount": -2743,"amount_details": {"atm_fee": null},"authorization": "iauth_1KrrbuDOiB2klwsKoFjQZhhd","balance_transaction": "txn_1KrrbwDOiB2klwsK1YkjJJRi","card": "ic_1Krqe5DOiB2klwsK44a35eiE","cardholder": "ich_1KrqL8DOiB2klwsKtBnZhzYr","created": 1650753567,"currency": "usd","dispute": null,"livemode": false,"merchant_amount": -2743,"merchant_currency": "usd","merchant_data": {"category": "advertising_services","category_code": "7311","city": "San Francisco","country": "US","name": "Aeros Marketing, LLC","network_id": "1234567890","postal_code": "94103","state": "CA"},"metadata": {},"type": "capture","wallet": null},{"id": "ipi_1Krrbvc62B2klwsKhuqUWqt1","object": "issuing.transaction","amount": -9999,"amount_details": {"atm_fee": null},"authorization": "iauth_1KrrbuDOiB2klwsKoFjQZhhd","balance_transaction": "txn_1KrrbwDOiB2klwsK1YkjJJRi","card": "ic_1Krqe5DOiB2klwsK44a35eiE","cardholder": "ich_1KrqL8DOiB2klwsKtBnZhzYr","created": 1650753567,"currency": "USD","dispute": null,"livemode": false,"merchant_amount": -9999,"merchant_currency": "usd","merchant_data": {"category": "fast_food","category_code": "7311","city": "San Francisco","country": "US","name": "Aeros Marketing, LLC","network_id": "1234567890","postal_code": "94103","state": "CA"},"metadata": {},"type": "capture","wallet": null}]}];const reduced = arr.reduce((prev, curr) => {prev.push({amount: curr.data[0].merchant_amount,id: curr.data[0].id,currency: curr.data[0].currency,category: curr.data[0].merchant_data.category});console.log(prev)return prev;}, []);
const getSearchTerm = delimiter => {let searchTerm = "";for (let i = 1; i < commands.length - 1; i++)searchTerm = searchTerm + commands[i] + delimiter;searchTerm += commands[commands.length - 1];return searchTerm;};