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J.J. Huang   2020-01-16   Node.js   瀏覽次數:

Node.js | NPM 使用介绍

簡介

npm(全稱Node Package Manager,即「node包管理器」)是Node.js預設的、以JavaScript編寫的軟體套件管理系統。
它是一個線上套件庫,可以下載各式各樣的Javascript套件來使用。

使用場景

  • 允許使用者從NPM伺服器下載別人編寫的第三方包到本機使用。
  • 允許使用者從NPM伺服器下載並安裝別人編寫的指令行程序到本機使用。
  • 允許使用者將自己編寫的包或指令行程序上傳到NPM伺服器供別人使用。

NPM 安裝

由於新版的Node.js已經集成了npm,所以之前npm也一併安裝好了。可以通過輸入

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npm -v

來測試是否成功安裝。

如果你安裝的是舊版本的npm,可以很容易得通過npm指令來升級。

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sudo npm install npm -g

NPM 指令介紹

安裝模組

npm安裝Node.js模組語法格式如下:

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npm install <Module Name>

我們使用npm指令安裝常用的Node.js web框架模組express

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npm install express

安裝好之後,express包就放在了工程目錄下的node_modules目錄中

因此在程式中只需要通過require('express')的方式就好,無需指定第三方包路徑。

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var express = require('express');

簡單的express範例:

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var express = require('express');
var app = express();

app.get('/', function (req, res) {
res.send('Hello World!');
});

app.listen(3000, function () {
console.log('Example app listening on port 3000!');
});

全域安裝、本機安装

npm的包安裝分為本機安裝(local)、全域安裝(global)兩種,從指令行來看,差別只是有沒有-g而已。

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npm install express ## 本機安裝
npm install express -g ## 全域安裝

如果出現以下錯誤:

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npm err! Error: connect ECONNREFUSED 127.0.0.1:8087

解決辦法為:

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npm config set proxy null
  • 本機安裝
    • 將安裝包放在./node_modules下(運行npm指令時所在的目錄),如果沒有node_modules目錄,會在當前執行npm指令的目錄下生成 node_modules目錄。
    • 可以通過require()來引入本機安裝的包。
  • 全局安裝
    • 將安裝包放在/usr/local下或者你node的安裝目錄。
    • 可以直接在指令行里使用。

查看安装訊息

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npm list
npm list -g ## 全域

如要查看某個模組版本號:

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npm list express

package.json

package.json是存在於任何Node應用程序/模組的根目錄和用於定義一個包的屬性。

Package.json的屬性:

名稱 說明
name 包的名稱
version 包的版本
description 包的描述
homepage 包主頁
author 包的作者
contributors 貢獻者到包的名字
dependencies 依賴關係的列表。NPM自動安裝所有在這裡的包node_module文件夾中提到的依賴關係
repository 包的庫類型和URL
main 包的入口點
keywords 關鍵字

打開package.json在當前node_modules/express/

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卸载模組

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npm uninstall express

更新模組

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npm update express

搜尋模組

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npm search express

總結

這篇文章僅僅介紹簡單常用的一些指令,還有一些指令沒有特別列出來,是因為將來才會特別用一篇文章來做介紹,像「建立模組」、「發布模組」之類的,這些到後面再來做介紹也不遲。

錯誤處理

no such file or directory, open ‘/package.json’

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$ npm install express --save
npm WARN saveError ENOENT: no such file or directory, open '/Users/morose/Documents/Temp/Example/package.json'
npm WARN enoent ENOENT: no such file or directory, open '/Users/morose/Documents/Temp/Example/package.json'
npm WARN Example No description
npm WARN Example No repository field.
npm WARN Example No README data
npm WARN Example No license field.

+ express@4.17.1
removed 1 package, updated 1 package and audited 764 packages in 2.289s

2 packages are looking for funding
run `npm fund` for details

found 0 vulnerabilities



╭────────────────────────────────────────────────────────────────╮
│ │
│ New patch version of npm available! 6.13.6 → 6.13.7 │
│ Changelog: https://github.com/npm/cli/releases/tag/v6.13.7 │
│ Run npm install -g npm to update! │
│ │
╰────────────────────────────────────────────────────────────────╯

原因:因為缺少package.json所以無法install

解決:將其初始化

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npm init -f

註:-f表示force的意思,不加這個,npm會讓你輸入一堆訊息,比如nameversion之類,如果只是做做實驗小demo,直接-fnpm幫你初始化package.json,並填充各種默認值,省事。

npm ERR! also called “”. Did you name your project the same

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$ npm install express --save
npm ERR! code ENOSELF
npm ERR! Refusing to install package with name "express" under a package
npm ERR! also called "express". Did you name your project the same
npm ERR! as the dependency you're installing?
npm ERR!
npm ERR! For more information, see:
npm ERR! <https://docs.npmjs.com/cli/install#limitations-of-npms-install-algorithm>

npm ERR! A complete log of this run can be found in:
npm ERR! /Users/morose/.npm/_logs/2020-02-06T02_44_10_640Z-debug.log

原因:安裝目錄的名稱與要安裝的模組名稱相同造成。

解決:將目錄名稱修改成非模組名稱,然後安裝。

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npm install express --save

註:--save表示將安裝的包加入依賴列表的意思,可以看下package.json裡的dependencies字段。後面再運行npm install,就會把所有依賴安裝下來。如果不加--save,什麼都不會安裝。


註:以上參考了
從零開始: 使用NPM套件
NPM 使用介绍
express Hello world 範例