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This article mainly introduces "what are the knowledge points of Node.js development". In the daily operation, I believe many people have doubts about the knowledge points of Node.js development. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the questions of "what are the knowledge points of Node.js development?" Next, please follow the editor to study!

Necessary skills

JavaScript

For a foreground developer, when considering mastering background skills, you don't need to spend a lot of energy learning to JavaScript. For complete rookies, if you want to master Node.js in the shortest possible time, you must understand the following concepts before going any further:

Arrow function (Arrow Functions)

Type (Types)

Expression (Expressions)

Function (Functions)

Syntax structure (Lexical Structures)

This

Loop (Loops) and scope (Scope)

Array objects (Arrays)

Literal template (Template Literals)

Strict mode (Strict Mode)

ES6/ES7

In addition, there are a large number of asynchronous programming solutions involved in Node.js. It is recommended to master the following concepts:

Timer (Timers)

Promises

Closure (Closures)

Event Loop (Event Loop)

Asynchronous programming (Async programming) and callback (callbacks)

Npm software package management

Node package Management (Node Package Manager,npm) provides the largest registration software library currently available, with more than 800,000 software packages available. The correct use of npm can greatly reduce the complexity of software package management, and it is very convenient to deal with the dependency problem in application development.

Npm provides three component modules:

Command line interface (Command Line Interface,CLI): CLI is the preferred way for most developers to run in a native terminal environment.

Registration Software Library (Registry): provides large-scale open JavaScript software and meta-information database.

Web site: you can find new packages and provide a small number of other npm features.

Npm can also manage various versions of the code and dependencies. If you use npx, you can run the package without downloading it.

Basic knowledge of Node.js

Event emitter (Event Emitter): as an object in Node.js, the Event Emitter sends a message after the operation is completed, triggering a specific event. Developers can also write code to listen for events emitted by Event Emitter. For example, once a specific foreground operation is completed, such as mouse click, button press and mouse movement and other interactive operations, further solutions need to be done in the background. At this time, the background Node.js environment uses the EventEmitter class to build the corresponding event resolution module to solve the operation event.

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Callback (Callback): callback is a function called after the execution of a specific task, which does not affect the simultaneous execution of other code and avoids blocking caused by asynchronous resolution. Callbacks are ubiquitous in view of the large number of asynchronous tasks that need to be addressed in Node.js. Callback is the key to seamless and fast execution of applications, and its operation mechanism is shown in the following figure:

Buffer class: a Node.js class designed to solve raw binary data, manipulating memory allocated outside the V8 engine. The Buffer class implements an array of integers that cannot be resized and provides a complete set of methods for manipulating binary data. For example, for in-memory integers that represent byte values between 0 and 255, using console.log () to output the Buffer instance gives a series of hexadecimal values.

Module system (Module System): using modules provided by the Node.js ecosystem, a small number of complex functions can be implemented. A module is reusable JavaScript code that implements specific functions.

Development skills

Version management system: master the use of git, GitHub, etc. In development, you should try to avoid irreversible changes caused by cross-modification of the code. Therefore, version control system management is needed in large-scale projects. To be familiar with the use of version control systems, developers should have a solid basic knowledge.

HTTP/HTTPS protocol: a good Node.js developer should have basic knowledge of transport protocol data transfer, because every background developer needs to have an in-depth understanding of how HTTP/HTTPS works. HTTPS uses an encryption protocol called TLS (Transport Layer Security) to encrypt communications. There are a lot of knowledge points to learn in the background environment, which is quite difficult for Web rookies. In short, basic Web communication consists of six request methods:

GET: get the representation of the resource

POST: create new resources

PUT: upgrade resourc

PATCH: partial modification of resources

DELETE: deletes the resource specified by URL

OPTIONS: request to specify the communication supported by the URL/ server.

Web framework

Note: this article lists only some of the recommended Web frameworks. When using Node.js to build personal projects, in order to reduce the difficulty of learning, it is recommended to choose a framework, otherwise it is very difficult to learn.

Express.js: provides minimal interfaces and tools for building applications. It is very flexible and easy to use, and a large number of npm modules can be directly plugged into Expresss.

Meteor.js: a know-it-all framework for building JavaScript applications, which provides built-in MongoDB and supports GraphQL. Run meteor create myapp to generate a HTML/JavaScript page with a MongoDB background. The use of Meteor.js can effectively help reduce project development time and simplify project maintenance. Of course, if you are just building a simple Web application, it is recommended to use Express.

Sails.js: a MVC framework that supports rapid construction of REST API, single page applications (SPA), and real-time APP. If developers consider practicing a small number of important skills, such as using WebSockets to support real-time operations, using agreed programming (convention over configuration) methods, etc., it is recommended to learn Sails.js.

Koa.js: if developers consider building a robust application that stands the test of time and is easy to maintain, Koa.js is a good choice. The Koa application is implemented as an object that contains an array of middleware functions, where the functions are executed in a stack.

Nest.js: this framework inherits the concept of Angular, is built using TypeScript, and uses Express.js at the bottom, so it is compatible with most Express middleware. Nest provides a good modular structure, and the code is organized in different modules to build efficient and well-extended applications.

Database management

Learning Node.js requires a lot of background skills. For a rookie, you can choose a database such as MySQL at first. Only by clarifying the basic knowledge of background system design, can we consider selecting the background outside the basic SQL database such as MySQL according to the needs of the project.

Note: relational databases are still mainstream. For example, relational table structures are still mainly used when modeling products, analogies, labels, and so on. Similar to a spreadsheet, a relational table consists of rows and columns.

Relational database management system

SQL Server: Microsoft's relational database product that supports standard ANSI SQL and also provides a unique SQL implementation of the product.

MySQL: an excellent relational database management system, open source backend software provided by Oracle, with the flexibility to improve code on demand. MySQL can be a good substitute for commercial database products such as Oracle and Microsoft SQL server.

PostgreSQL: open source products supported by large development teams that run on most major operating systems such as Linux, UNIX, and Windows. PostgreSQL supports most standard SQL queries, as well as complex SQL queries, foreign keys, triggers, transactions, MVCC, stream replication, and so on.

An improved version of MariaDB:MySQL with additional built-in features, security and performance improvements. In short, MariaDB performs better than MySQL, and it is recommended to use MariaDB in large-scale applications. For example, MariaDB's large connection pool supports more than 200000 concurrent connections, which is significantly better than MySQL.

Cloud database service

Azure CosmosDB: a globally distributed database service that supports remote management of data. For large-scale applications, cloud databases have advantages in scalability and manageability. Microsoft Azure completely simplifies extensibility and distribution capabilities, supporting multiple data models in the same background, and can be used for document, key, relational, and graph models at the same time. The service does not depend on any schema, so it can be called a NoSQL database, but a query language that supports ACID transactions can be used.

Amazon DynamoDB: very suitable for customers with SQL experience, providing fully managed NoSQL database services with high performance, predictability and good scalability. DynamoDB supports the creation of relational tables that can store and retrieve data of any size and provide requests for any level of service.

NoSQL database

MongoDB: a document-oriented NoSQL database suitable for large-scale data storage. Similar to tables, which are the foundation of relational databases, MongoDB uses collections (Collection) and documents (Document). Among them, the document contains key-value pairs, which is the basic data unit of MongoDB. The collection contains a series of documents and functions that align tables in a relational database.

Redis: can be used for database, cache, and message broker (Message Broker). Redis uses data structures such as strings, hashes, lists, collections, bitmaps, hyperloglog, and spatio-temporal indexes to store data as keys. The following examples are given:

Assume that the application must address the different actions of the authorized customer. Each time the customer identity is verified, it is necessary to obtain the authorization of the access control module in the application. There are many ways to implement such security mechanisms. For example, the standard JOSE (JavaScript object signing and encryption) framework ensures the security of application data. However, in the face of multiple authorizations, the application is also difficult to expand. In addition to sending the authorization list to the customer, another solution is to store the customer authorization in some form of database. Authorization is provided in the form of key-value pairs (also known as tokens), and the customer must provide a key value for verification.

Apache Cassandra:Facebook created a highly scalable, high-performance distributed database, designed for the physical distribution of massive data, to achieve no single point of failure storage. Unlike other relational database systems, Cassandra refers to Amazon DynamoDB in its distributed design, and the data model uses Google BigTable.

LiteDB: an ultra-lightweight, high-performance .NET NoSQL embedded in the database to achieve serverless document storage. LiteDB is used for small desktop applications and Web applications to build a separate database based on each customer's account.

Search engine

Note: the following examples illustrate why you need to understand search engine technology. If you use Google search engine, it itself is a complete Web application. For background frameworks such as Solr and ElasticSearch, they create indexes on all types of datasets, which in turn provide search capabilities on the server. Solr supports search engine sites with millions of customers.

ElasticSearch: a search and analysis engine based on Apache Lucene and developed with Java to realize real-time storage and analysis of massive data. Its high performance comes from searching indexes rather than text, and the core is based on structured documents rather than relational tables and schemas, providing rich REST API storage and search data. ElasticSearch can be thought of as a server that resolves JSON requests and returns JSON data.

Solr: provides advanced real-time search functions, including field search, Boolean query, phrase query, fuzzy query, syntax check, auto-fill and so on.

Caching

Note: caching uses in-memory file copies to reduce network calls and provide faster network response.

Memory cache

This technique uses the server's memory in most cases, so it is often referred to as memory caching. Part of the server's memory is used as a cache to store all the data needed to reduce application network calls. The node cache (node-cache) and memory cache (memory-cache) software library provided by Node.js solves the memory cache on the Node server very well.

Distributed cache

Distributed cache integrates multiple network memory into a single in-memory data storage, which is used to cache the final data and provide fast access to the data. This technology is especially suitable for large-scale data and a large number of network calls to achieve incremental expansion and expansion of cache capacity by adding more servers in the cluster. Redis is currently the most widely used distributed memory, and it is recommended to further understand Memcached.

Template engine

The template engine supports the use of static template files in application development, and replaces the variables in the template files to actual values at run time to generate HTML files sent to users. A small number of widely used template engines are listed below.

Mustache.js

Handlebars

EJS

Real-time communication

Socket.io: for learners who start to come into contact with background development, understanding the real-time communication of Socket.io requires a lot of knowledge, and the main underlying logic is between the client and the server. Socket.io supports two-way data flow between the user and the server, which can be regarded as a synchronous data flow behavior to realize real-time communication between two terminals. This requires the user to support Socket.IO in the browser and inherit the Socket.IO software package on the server side so that the data can be sent in the form of JSON requests.

API client

REST

Before REST was proposed, API was developed using remote procedure call (RPC), similar to locally executed code. During this period, many technologies used a technology stack similar to RPC and did not fundamentally deal with the problem until REST proposed a better way to build a Web-based API.

The REST architecture uses basic HTTP calls for communication, avoiding complex communication methods such as COBRA, COM +, RPC, and so on. In REST, calls are message-based and rely on the HTTP standard to describe messages. In Node.js ecology, node-rest-client and Axios are recommended. These two software libraries provide good support for fast Web applications.

GraphQL

GraphQL is a good substitute for REST. It uses API as a priority to provide users with accurate requested data, and is a flexible and developer-friendly alternative to deployment using GraphiQL IDE. GraphQL has several advantages, including adding and disabling data fields without affecting existing queries, and supporting multiple ways to build API.

test

Unit testing framework

Unit testing realizes the isolation testing of each unit and component. Wherein, the unit may be the smallest testable part of the application. Here is a list of the best unit testing frameworks for Node.js:

Jest: a testing framework provided by Facebook that is widely used because of its simplicity. Jest has the best documentation compared to all other testing frameworks and supports parallel testing, which means that individual tests can be run independently using separate processes to maximize performance.

Mocha: provides the original standard unit testing framework for Node applications, supports asynchronous operations such as callbacks, and supports Promise with highly extensible and self-setting assertions.

Chai: supports use with Mocha, can be used as Node.js 's TDD/BDD assertion library, and can match any JavaScript-based testing framework.

Simulation test (Mocking)

The smaller the size of the unit test, the better, and perform it as lightweight as possible. However, in a few cases, the test object has a dependency on the rest of the object.

For example, for objects that need to communicate with domain servers or Web Service, fast, lightweight tests cannot be performed, and Mocking tests are required. Running the Mocking test does not require any actual database, or any type of connection, and only returns the object that gives the expected result. Mocking tests use only a small number of basic objects to simulate the actual test results, so you can run the tests faster without all limitations.

At this point, the study of "what are the knowledge points of Node.js development" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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