说说包管理工具 NPM 的基本用法

NPM 是随同 NodeJS 一起安装的包管理工具，可以解决 NodeJS 代码部署上的很多问题，常见的使用场景有以下几种：

允许我们从 NPM 服务器下载第三方编写的包到本地使用。
允许我们从 NPM 服务器下载并安装第三方编写的命令行程序到本地使用。
允许我们将自己编写的包或命令行程序上传到 NPM 服务器供他人使用。

新版的 nodejs 已经集成了 npm ，所以 npm 不需要单独安装。

1 淘宝 NPM 镜像

因为国内直接使用 npm 的官方镜像非常慢，所以推荐使用淘宝 NPM 镜像。这是一个完整 npmjs.org 镜像，我们可以用此代替官方版本(只读)，同步频率目前为 10分钟一次，保证与官方服务同步。

安装指令：

npm install -g cnpm --registry=http://registry.npm.taobao.org

也可以用此指令，更新淘宝 NPM 镜像包。

安装成功后，就可以使用 cnpm 命令来安装模块了：

cnpm install [name]

淘宝 NPM 镜像完整说明：http://npm.taobao.org/

2 安装模块

npm 安装 Node.js 模块语法格式如下：

npm install <Module Name>

比如想安装 request 模块，就可以这样：

npm install request

不过还是建议用 cnpm 指令来安装模块，会更快些。

然后就可以通过 require 调用我们刚刚安装的模块。在 WebStorm 中，会弹出提示，让我们把模块写到 package.json 文件中。

通过 Alt + Shift + Enter 指令，就可以自动创建 package.json 文件并添加好对应的模块：

{"name": "deniro-nodejs","version": "1.0.0","dependencies": {"request": "latest"}
}

3 全局安装与本地安装

npm 的包安装分为本地安装（local）、全局安装（global）两种，全局安装命令比本地安装命令，多了一个 -g。

cnpm install request  # 本地安装
cnpm install request -g #全局安装

二者区别如下：

	安装包路径	调用方式
本地安装	放在 ./node_modules 下（运行 npm 命令时所在的目录），如果没有 node_modules 目录，会在当前执行 npm 命令的目录下生成 node_modules 目录。	通过 require() 来引入本地安装的包。
全局安装	放在 /usr/local 下或者 node.js 的安装目录。	可以直接在命令行里使用。

全局安装 request 模块时，会输出如下内容：

[1/20] aws-sign2@~0.7.0 installed at node_modules\_aws-sign2@0.7.0@aws-sign2
[2/20] aws4@^1.8.0 installed at node_modules\_aws4@1.9.1@aws4
[3/20] caseless@~0.12.0 installed at node_modules\_caseless@0.12.0@caseless
[4/20] is-typedarray@~1.0.0 installed at node_modules\_is-typedarray@1.0.0@is-typedarray
[5/20] forever-agent@~0.6.1 installed at node_modules\_forever-agent@0.6.1@forever-agent
[6/20] isstream@~0.1.2 installed at node_modules\_isstream@0.1.2@isstream
[7/20] oauth-sign@~0.9.0 installed at node_modules\_oauth-sign@0.9.0@oauth-sign
[8/20] performance-now@^2.1.0 installed at node_modules\_performance-now@2.1.0@performance-now
[9/20] json-stringify-safe@~5.0.1 installed at node_modules\_json-stringify-safe@5.0.1@json-stringify-safe
[10/20] combined-stream@~1.0.6 installed at node_modules\_combined-stream@1.0.8@combined-stream
[11/20] form-data@~2.3.2 installed at node_modules\_form-data@2.3.3@form-data
[12/20] extend@~3.0.2 installed at node_modules\_extend@3.0.2@extend
[13/20] qs@~6.5.2 installed at node_modules\_qs@6.5.2@qs
[14/20] mime-types@~2.1.19 installed at node_modules\_mime-types@2.1.26@mime-types
[15/20] safe-buffer@^5.1.2 installed at node_modules\_safe-buffer@5.2.0@safe-buffer
[16/20] tunnel-agent@^0.6.0 installed at node_modules\_tunnel-agent@0.6.0@tunnel-agent
[17/20] uuid@^3.3.2 installed at node_modules\_uuid@3.4.0@uuid
[18/20] tough-cookie@~2.5.0 installed at node_modules\_tough-cookie@2.5.0@tough-cookie
[19/20] har-validator@~5.1.3 installed at node_modules\_har-validator@5.1.3@har-validator
[20/20] http-signature@~1.2.0 installed at node_modules\_http-signature@1.2.0@http-signature
All packages installed (47 packages installed from npm registry, used 1s(network 1s), speed 857.68kB/s, json 46(93.67kB), tarball 968.13kB)

4 常用指令

（1）查看所有全局安装的模块

npm list -g

输出形如：

| | | +-- aproba@2.0.0 deduped
| | | +-- figgy-pudding@3.5.1 deduped
| | | `-- npm-registry-fetch@4.0.3 deduped
| | +-- npm-registry-fetch@4.0.3
| | | +-- bluebird@3.5.5 deduped
| | | +-- figgy-pudding@3.5.1 deduped
| | | +-- JSONStream@1.3.5 deduped
| | | +-- lru-cache@5.1.1 deduped
...

（2）查看某个模块的版本号

npm list [name]

输出形如：

deniro-nodejs@1.0.0 F:\WebstormProjects\deniro-nodejs
`--  request@2.88.2

输出格式为：projectName@projectVersion /path/to/project/folder。

（3）更新模块指令

npm update [name]

（4）搜索模块指令

npm search [name]

比如搜索 request 模块，会输出以下内容：

NAME                      | DESCRIPTION          | AUTHOR          | DATE       | VERSION  | KEYWORDSsuperagent                | elegant & feature…   | =defunctzombie… | 2020-02-17 | 5.2.2    | agent ajax ajax api async await axios cancel client frisbee got http http h
tt
request-promise           | The simplified HTTP… | =analog-nico…   | 2019-11-04 | 4.2.5    | xhr http https promise request then thenable bluebird
request-promise-native    | The simplified HTTP… | =analog-nico…   | 2019-11-04 | 1.0.8    | xhr http https promise request then thenable native
needle                    | The leanest and…     | =tomas          | 2020-04-03 | 2.4.1    | http https simple request client multipart upload proxy deflate timeout char
s
request-progress          | Tracks the download… | =satazor        | 2016-12-01 | 3.0.0    | progress request mikeal size bytes percent percentage speed eta etr
supertest                 | SuperAgent driven…   | =defunctzombie… | 2019-03-15 | 4.0.2    | superagent request tdd bdd http test testing
got                       | Human-friendly and…  | =sindresorhus…  | 2020-03-24 | 10.7.0   | http https http2 get got url uri request simple curl wget fetch net networke
graphql-request           | [![CircleCI](https:… | =schickling…    | 2018-08-10 | 1.8.2    | graphql request fetch graphql-client apollo
morgan                    | HTTP request logger… | =dougwilson     | 2020-03-20 | 1.10.0   | express http logger middleware
axios-mock-adapter        | Axios adapter that…  | =ctimmerm       | 2020-03-22 | 1.18.1   | axios test mock request stub adapter
cookie-parser             | Parse HTTP request…  | =defunctzombie… | 2020-03-15 | 1.4.5    | cookie middleware
raf                       | requestAnimationFra… | =chrisdickinson… | 2018-11-02 | 3.4.1    | requestAnimationFrame polyfill
request-promise-core      | Core Promise…        | =analog-nico    | 2019-11-03 | 1.1.3    | xhr http https promise request then thenable core
popsicle                  | Advanced HTTP…       | =blakeembrey    | 2019-11-03 | 12.0.5   | request http middleware node ajax browser promise
sync-request              | Make synchronous…    | =forbeslindesay | 2019-03-17 | 6.1.0    | request http https cache browserify synchronous sync
http-signature            | Reference…           | =arekinath…     | 2020-04-02 | 1.3.4    | https request
cacheable-request         | Wrap native HTTP…    | =lukechilds     | 2020-01-21 | 7.0.1    | HTTP HTTPS cache caching layer cacheable RFC 7234 RFC 7234 compliant
light-my-request          | Fake HTTP injection… | =delvedor…      | 2020-03-26 | 3.7.4    | http inject fake request server
proxy-addr                | Determine address…   | =dougwilson     | 2020-02-24 | 2.0.6    | ip proxy x-forwarded-for
make-fetch-happen         | Opinionated,…        | =ruyadorno…     | 2020-03-12 | 8.0.4    | http request fetch mean girls caching cache subresource integrity

（5）查看 npm 版本号

npm -v

5 package.json

package.json 位于模块包的根目录下（模块安装成功后，会放在 node_modules 下），用于定义模块包的属性。比如，request 模块的 package.json 配置如下：

{"name": "request","description": "Simplified HTTP request client.","keywords": ["http","simple","util","utility"],"version": "2.88.2","author": "Mikeal Rogers <mikeal.rogers@gmail.com>","repository": {"type": "git","url": "https://github.com/request/request.git"},"bugs": {"url": "http://github.com/request/request/issues"},"license": "Apache-2.0","engines": {"node": ">= 6"},"main": "index.js","files": ["lib/","index.js","request.js"],"dependencies": {"aws-sign2": "~0.7.0","aws4": "^1.8.0","caseless": "~0.12.0","combined-stream": "~1.0.6","extend": "~3.0.2","forever-agent": "~0.6.1","form-data": "~2.3.2","har-validator": "~5.1.3","http-signature": "~1.2.0","is-typedarray": "~1.0.0","isstream": "~0.1.2","json-stringify-safe": "~5.0.1","mime-types": "~2.1.19","oauth-sign": "~0.9.0","performance-now": "^2.1.0","qs": "~6.5.2","safe-buffer": "^5.1.2","tough-cookie": "~2.5.0","tunnel-agent": "^0.6.0","uuid": "^3.3.2"},"scripts": {"test": "npm run lint && npm run test-ci && npm run test-browser","test-ci": "taper tests/test-*.js","test-cov": "nyc --reporter=lcov tape tests/test-*.js","test-browser": "node tests/browser/start.js","lint": "standard"},"devDependencies": {"bluebird": "^3.2.1","browserify": "^13.0.1","browserify-istanbul": "^2.0.0","buffer-equal": "^1.0.0","codecov": "^3.0.4","coveralls": "^3.0.2","function-bind": "^1.0.2","karma": "^3.0.0","karma-browserify": "^5.0.1","karma-cli": "^1.0.0","karma-coverage": "^1.0.0","karma-phantomjs-launcher": "^1.0.0","karma-tap": "^3.0.1","nyc": "^14.1.1","phantomjs-prebuilt": "^2.1.3","rimraf": "^2.2.8","server-destroy": "^1.0.1","standard": "^9.0.0","tape": "^4.6.0","taper": "^0.5.0"},"greenkeeper": {"ignore": ["hawk","har-validator"]},"__npminstall_done": "Sat Apr 18 2020 10:38:30 GMT+0800 (GMT+08:00)","_from": "request@2.88.2","_resolved": "https://registry.npm.taobao.org/request/download/request-2.88.2.tgz?cache=0&sync_timestamp=1581439349114&other_urls=https%3A%2F%2Fregistry.npm.taobao.org%2Frequest%2Fdownload%2Frequest-2.88.2.tgz"
}

具体属性说明如下：

属性	说明
name	包名。
version	包的版本号。
description	描述。
homepage	官网主页 url 。
author	作者姓名。
contributors	贡献者姓名。
dependencies	依赖包列表。如果依赖包没有安装，npm 会自动将依赖包安装在 node_module 目录下。
repository	包代码托管类型，可以是 git 或 svn，git 可在 Github 上。
main	指定了程序的主入口文件，require(‘moduleName’) 就会加载这个文件。这个字段的默认值是模块根目录下面的 index.js。
keywords	关键字

6 创建模块

我们所开发的项目，其实本质上也是模块，因此也是通过 npm 进行管理的。

我们可以使用 NPM 生成 package.json 文件，生成的文件包含了这个项目的一些基本的内容。

创建模块指令为：npm init，执行过程中会以交互的方式，让我们输入包名、版本号、描述、入口文件、测试命令、git 仓库地址、关键字、作者、许可证等信息。必填项会提供默认值，我们可以修改这些默认值。

This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.See `npm help json` for definitive documentation on these fields
and exactly what they do.Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.Press ^C at any time to quit.
package name: (deniro-nodejs)
version: (1.0.0)
description: study node.js
entry point: (create_app.js) index.js
test command: make test
git repository:
keywords:
author: Deniro Lee
license: (ISC)
About to write to F:\WebstormProjects\deniro-nodejs\package.json:{"name": "deniro-nodejs","version": "1.0.0","dependencies": {"request": "latest"},"description": "study node.js","main": "index.js","devDependencies": {},"scripts": {"test": "make test"},"author": "Deniro Lee","license": "ISC"
}Is this OK? (yes) yes

执行后，就会在 package.json 中，加入以上这些配置项：

{"name": "deniro-nodejs","version": "1.0.0","dependencies": {"request": "latest"},"description": "study node.js","main": "index.js","devDependencies": {},"scripts": {"test": "make test"},"author": "Deniro Lee","license": "ISC"
}

7 版本号

使用 NPM 下载和发布代码时都会接触到版本号。 NPM 使用语义版本号来管理代码。语义版本号分为 X.Y.Z 三位，分别代表主版本号、次版本号和补丁版本号。当代码变更时，版本号按以下原则更新。

如果只是修复 bug ，需要更新 Z 位；
如果是新增了功能，但是向下兼容，需要更新 Y 位；
如果有大变动，向下不兼容，需要更新 X 位。