Created
July 11, 2018 04:27
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Get most popular Pizza
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| /* | |
| Node v8.9.0 | |
| $ node popular_pizzas.js | |
| Most popular pizza is: pepperoni | |
| */ | |
| const http = require('http'); | |
| fetchPizzas() | |
| .then(reducePizzasToHash) | |
| .then(countPizzas) | |
| .then(sortPizzas) | |
| .then(getPopularPizza) | |
| .then(popularPizza => console.log(`Most popular pizza is: ${popularPizza}`)) | |
| function fetchPizzas() { | |
| return new Promise(function (resolve, reject) { | |
| http.get('http://files.olo.com/pizzas.json') | |
| .on('error', (e) => { | |
| return reject(`Got error: ${e.message}`) | |
| }) | |
| .on('response', res => { | |
| const { statusCode } = res; | |
| // check for errors | |
| let error; | |
| if (statusCode !== 200) { | |
| error = new Error(`Request Failed.\n Status Code: ${statusCode}`); | |
| } | |
| if (error) { | |
| console.error(error.message); | |
| // consume response data to free up memory | |
| res.resume(); | |
| return reject(error.message); | |
| } | |
| // concat response stream | |
| res.setEncoding('utf8'); | |
| let rawData = ''; | |
| res.on('data', (chunk) => { rawData += chunk; }); | |
| // parse response | |
| res.on('end', () => { | |
| try { | |
| return resolve(JSON.parse(rawData)); | |
| } catch (e) { | |
| console.error(e.message); | |
| } | |
| }); | |
| }); | |
| }) | |
| } | |
| function reducePizzasToHash(pizzas) { | |
| return pizzas.map(({ toppings: toppings }) => { | |
| return Buffer.from(toppings.join(", ")).toString('base64') | |
| }) | |
| } | |
| function countPizzas(pizzaHashes) { | |
| return pizzaHashes.reduce((acc, currentPizzaHash) => Object.assign(acc, { [currentPizzaHash]: (acc[currentPizzaHash] | 0) + 1 }), {}) | |
| } | |
| function sortPizzas(pizzaCounts) { | |
| return Object.keys(pizzaCounts).sort(function (a, b) { return pizzaCounts[b] - pizzaCounts[a] }) | |
| } | |
| function getPopularPizza(pizzas) { | |
| return Buffer.from(pizzas[0], 'base64').toString('ascii') | |
| } |
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