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<\/p>\nA few months ago, I had to build a full-stack app having only front-end experience. This is an overview of backend tools and practices if you discover yourself in the same situation.<\/p>\n
<\/p>\n
To write an app, you\u2019ll have to figure out three things: a programming language for the backend, a database to store data, and infrastructure.<\/p>\n
Popular backend languages include Ruby, Python, JavaScript (Node.js), Java and PHP. If you\u2019re a front-end developer, start with Node.js<\/mark> \u2013 things would be way easier.<\/p>\n I\u2019ll cover databases and infrastructure in the next parts.<\/p>\n Node.js enables you to write servers in JavaScript. It\u2019s a JavaScript engine similar to the one Google Chrome has. You pass it a JS file, and the engine runs it:<\/p>\n To launch a real server, you\u2019ll need to call a specific method provided by Node.js (e.g, The primary thing you need to know about Node.js is that it performs all long actions (like reading data from a database) asynchronously \u2013 using callbacks. This means that to make a DB request, you don\u2019t do this:<\/p>\n but do this instead:<\/p>\n Under the hood, Node.js sends a request to the database and immediately continues executing the code. And when the request completes, Node.js calls the callback and passes the data to it. This helps to write servers that handle lots of requests at the same time.<\/p>\n<\/div>\n<\/div>\n Yes. If you don\u2019t like passing functions into other functions, there\u2019re a couple of alternatives:<\/p>\n Option A:<\/b> use promises instead of callbacks. You\u2019ll still have to pass functions around \u2013 but you\u2019ll write code without excessive nesting which often happens with callbacks:<\/p>\n<\/div>\n<\/div>\n Option B:<\/b> use Many native Node.js APIs (like However, avoid using them on real servers \u2013 or the server would die just from a few simultaneous clients. (These APIs are useful in console scripts though.)<\/p>\n Use Express<\/a>:<\/p>\n Express is useful for building static servers and REST APIs.<\/p>\n In a real app, apart from an HTTP server, you\u2019ll need to implement a few more things. Here\u2019re the common solutions for them:<\/p>\n That\u2019s it! The next part of the guide will introduce you into databases (specifically, into MySQL).<\/p>\n","protected":false},"excerpt":{"rendered":"OK, I\u2019ve just installed Node.js. What is it?#<\/a><\/h2>\n
\/\/ index.js\r\nconsole.log('42');\r\n<\/code><\/pre>\n# Shell\r\n$ node .\/index.js\r\n42\r\n<\/code><\/pre>\n\ncreateServer()<\/code> docs<\/a><\/div>\n\ncreateServer()<\/code> from the net<\/code> module). In practice, a few people do this \u2013 almost everyone uses high-level wrappers.<\/p>\n<\/div>\n<\/div>\nI\u2019ve heard a bit about Node.js and callbacks. What\u2019s the deal with them?#<\/a><\/h2>\n
\nCallback is a function that you pass into other function. It\u2019s called when a specific action completes. MDN docs<\/a><\/div>\n\nconst data = sql.query('SELECT name from users');\r\nconsole.log(data);\r\n<\/code><\/pre>\nsql.query('SELECT name from users', (error, data) => {\r\n console.log(data);\r\n});\r\n<\/code><\/pre>\n<\/div>\n<\/div>\n\nRelated: Why Asynchronous?<\/a> \u00b7 Understanding Node.js Event Loop<\/a><\/div>\n\nCan I write code without callbacks?#<\/a><\/h2>\n
\n
\nWhat a promise is<\/a><\/div>\n\n\nUse util.promisify<\/code><\/a> to adapt native callback-based APIs to promises<\/div>\n\n\/\/ With callbacks\r\nconst fs = require('fs');\r\n\r\nfs.readFile('.\/text.txt', (err, data) => {\r\n console.log(data);\r\n});\r\n\r\n\/\/ With promises\r\nconst fs = require('fs');\r\nconst util = require('util');\r\nconst readFile = util.promisify(fs.readFile);\r\n\r\nreadFile('.\/text.txt')\r\n .then((data) => {\r\n console.log(data);\r\n })\r\n .catch((err) => {\r\n \/\/ ...\r\n });\r\n<\/code><\/pre>\n<\/div>\n<\/div>\n<\/li>\n\nWhat async\/await<\/code> is<\/a><\/div>\n\nasync\/await<\/code> with promise APIs. This lets you write code that looks synchronous:<\/p>\n<\/div>\n<\/div>\n\nasync\/await<\/code> is available with Node.js 7.6+.<\/div>\n\n\/\/ With callbacks\r\nconst fs = require('fs');\r\n\r\nfs.readFile('.\/text.txt', (err, data) => {\r\n console.log(data);\r\n});\r\n\r\n\/\/ With async\/await\r\nconst fs = require('fs');\r\nconst util = require('util');\r\nconst readFile = util.promisify(fs.readFile);\r\n\r\ntry {\r\n const data = await readFile('.\/text.txt')\r\n console.log(data);\r\n} catch (err) {\r\n \/\/ ...\r\n};\r\n<\/code><\/pre>\n<\/div>\n<\/div>\n<\/li>\n<\/ul>\nfs.readFile<\/code><\/a>) also have synchronous alternatives (like fs.readFileSync<\/code><\/a>):<\/p>\nconst fs = require('fs');\r\nconst data = fs.readFileSync('.\/text.txt');\r\n<\/code><\/pre>\nOK, how do I create a server?#<\/a><\/h2>\n
const express = require('express');\r\nconst app = express();\r\n\r\n\/\/ \u2193 Define a REST request\r\napp.get('\/api\/user', (req, res) => {\r\n res.json({ name: 'Jason Bourne' });\r\n});\r\n\r\n\/\/ \u2193 Ask the server to return statis files\r\n\/\/ from the `public` dir (if the \/api\/user route didn\u2019t match)\r\napp.use('*', express.static('public'));\r\n\r\napp.listen(3000, () => {\r\n console.log('Server is listening on port 3000')\r\n});\r\n<\/code><\/pre>\nHow do I build something real?#<\/a><\/h2>\n
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