npm入手笔记0x001-项目初始化和包增删改

0x001 概述

npm是一个包管理工具，本文章基本算是对官方文档的解读、翻译和实操笔记，顺便说明使用npm中的坑。

0x002 安装Node.js

安装方式参照Node.js官方文档便可，安装完成后，命令行键入node -v成功执行说明安装成功了

$ node -v
v6.3.1

顺便检查一下npm版本并更新它

$ npm -v
5.3.0
$ npm install npm@latest -g

/usr/local/bin/npm -> /usr/local/lib/node_modules/npm/bin/npm-cli.js
/usr/local/bin/npx -> /usr/local/lib/node_modules/npm/bin/npx-cli.js
+ npm@5.4.1
added 22 packages, removed 22 packages and updated 133 packages in 11.208s


   ╭─────────────────────────────────────╮
   │                                     │
   │   Update available 5.3.0 → 5.4.1    │
   │     Run npm i -g npm to update      │
   │                                     │
   ╰─────────────────────────────────────╯

0x003 本地安装包

新建一个项目文件夹

mkdir 0x003-install-local
cd 0x003-install-local

安装loadash

$ npm install lodash
npm WARN saveError ENOENT: no such file or directory, open '/MY_PROJECT/PROJECT_OWN/NodeJS/npm/package.json'
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN enoent ENOENT: no such file or directory, open '/MY_PROJECT/PROJECT_OWN/NodeJS/npm/package.json'
npm WARN npm No description
npm WARN npm No repository field.
npm WARN npm No README data
npm WARN npm No license field.

+ lodash@4.17.4
added 1 package in 0.862s

成功安装包以后，将会发生如下的事情：

• 在项目的目录会生成一个node_modules文件夹，里面放置了咱们项目全部的本地依赖包

  $ cd node_modules
  $ ls
  lodash

• 若是该项目存在package.json文件，将会把该lodash加入到项目的依赖中，这里没有package.json，因此安装的时候有个WARN。

• 生成一个package-lock.json,将项目的依赖版本锁定，这样迁移的时候，从新安装依赖就会安装指定版本的包（新版本才有，待验证）。

引用并执行

$ vim index.js 

// index.js
var lodash = require('lodash');
var output = lodash.without([1, 2, 3], 1);
console.log(output);

$ node index.js
[ 2, 3 ]

若是安装出错，好比写错了包名，将会发生如下事情：

• 命令行报错

npm install loadashsh
npm ERR! code E404
npm ERR! 404 Not Found: loadashsh@latest

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/FollowWinter/.npm/_logs/2017-09-10T11_37_44_504Z-debug.log

0x004 使用package.json

能够本身新建一个文件编写package.json,也能够直接使用npm init来初始化一个

$ mkdir 0x004-use-package_json
$ cd 0x004-use-package_json/
$ npm init
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: (0x004-use-package_json) 
version: (1.0.0) 
description: 
entry point: (index.js) 
test command: 
git repository: 
keywords: 
author: 
license: (ISC) 
About to write to /MY_PROJECT/PROJECT_OWN/NodeJS/npm/0x004-use-package_json/package.json:

{
  "name": "0x004-use-package_json",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}

Is this ok? (yes)

该命令是一个交互式命令，能够根据提示输入相应信息生成相应的package.json，命令提示后面的()中为提示内容，能够选择一路enter，而后再去修改package.json。执行成功后，将会在项目中生成package.json文件。

// package.json
{
  "name": "0x004-use-package_json", 
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}

再一次安装包

$ npm install lodash
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN 0x004-use-package_json@1.0.0 No description
npm WARN 0x004-use-package_json@1.0.0 No repository field.

+ lodash@4.17.4
added 1 package in 1.378s
//package.json
{
  "name": "0x004-use-package_json",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "lodash": "^4.17.4"
  }
}

能够发现，多了一个dependencies节点，该节点保存了项目全部的依赖，固然咱们也能够经过对该节点的修改，改变项目的依赖，好比删除lodash,或者改变lodash版本。
删除dependencies中的lodash以后再执行

$ npm install 
npm WARN 0x004-use-package_json@1.0.0 No description
npm WARN 0x004-use-package_json@1.0.0 No repository field.

removed 1 package in 0.249s
$ cd node_modules
$ ls -al
.    ..

能够看出，lodash包已经被移除
npm install能够根据package.json的指示安装、更新、删除依赖。

0x005 更新依赖

npm update

0x006 删除依赖

$ npm uninstall lodash
npm WARN 0x004-use-package_json@1.0.0 No description
npm WARN 0x004-use-package_json@1.0.0 No repository field.

removed 1 package in 0.247s

0x007 全局包管理

和安装本地包没有区别，只是加了个-g参数,表示global

$ npm install -g jshint
/usr/local/bin/jshint -> /usr/local/lib/node_modules/jshint/bin/jshint
+ jshint@2.9.5
added 31 packages in 41.728s

同理包的更新和删除也无异，

$ npm install -g jshint
$ npm update -g jshint
$ npm uninstall -g jshint
removed 31 packages in 0.365s

0x008 总结

一篇文章太长，打起字来就会卡顿， 我打了不少字吗？

• npm init: 初始化项目，生成package.json

• npm install [<package_name> [--save|--save-dev] -g]:

  • 根据项目中的package.json初始化项目、更新依赖

  • 若是指定了<package_name>，则安装<package_name>

• npm update [<package_name>]:

  • 更新项目依赖到新版本

  • 若是指定了<package_name>，则更新<package_name>

• npm uninstall <package_name>: 移除<package_name>依赖,并更新dependencies或者dependencies-dev中的<package_name>节点

0x009 资源

• 项目github