nodejs用npm创建项目

要创建package.json文件，运行以下命令：

> npm init

此为初始化项目命令，会在你运行此命令的文件夹根目录下创建项目配置文件：package.json。同时每行会出现一个问题，你输入答案后会出来另一个问题。这些问题最终会记录到package.json文件中。

也可以运行带--yes或-y标签的npm init命令，来生成默认的package.json文件：

> npm init --yes

或者

> npm init --y

比如最近做的相关项目的package.json就是以下这个样子。

{
  "name": "devil",
  "version": "1.0.0",
  "description": "",
  "main": "",
  "scripts": {
    "test": "mocha --compilers js:babel-core/register assets/es6/test"
  },
 "repository": {
    "type": "git",
    "url": "............"
  },
  "author": "bluesky",
  "license": "ISC",
  "devDependencies": {
    "babel-core": "^6.18.2",
    "babel-eslint": "^7.2.2",
    "babel-preset-es2015": "^6.18.0",
    "babel-preset-stage-0": "^6.16.0",
    "babelify": "^7.3.0",
    "browser-sync": "^2.9.11",
    "browserify": "^14.3.0",
    "chai": "^3.5.0",
    "coffee-script": "^1.10.0",
    "coffeeify": "^2.1.0",
    "eslint": "^3.10.2",
    "gulp": "^3.9.0",
    "gulp-autoprefixer": "^3.1.0",
    "gulp-babel": "^6.1.2",
    "gulp-bless": "^3.1.0",
    "gulp-coffee": "^2.3.1",
    "gulp-compass": "^2.1.0",
    "gulp-concat": "^2.6.0",
    "gulp-csso": "^3.0.0",
    "gulp-eslint": "^3.0.1",
    "gulp-if": "^2.0.2",
    "gulp-jshint": "^2.0.4",
    "gulp-load-plugins": "^1.0.0",
    "gulp-notify": "^3.0.0",
    "gulp-plumber": "^1.0.1",
    "gulp-rename": "^1.2.2",
    "gulp-rev": "^7.1.2",
    "gulp-rev-replace": "^0.4.3",
    "gulp-sass": "^3.1.0",
    "gulp-sequence": "^0.4.6",
    "gulp-sourcemaps": "^2.4.1",
    "gulp-uglify": "^2.1.2",
    "gulp-watch": "^4.3.5",
    "gulp.spritesmith": "^6.2.1",
    "jshint": "^2.9.2",
    "jshint-stylish": "^2.0.1",
    "merge-stream": "^1.0.1",
    "minimatch": "^3.0.2",
    "minimist": "^1.2.0",
    "mocha": "^3.2.0",
    "require-dir": "^0.3.0",
    "rimraf": "^2.6.1",
    "run-sequence": "^1.1.4",
    "vinyl-buffer": "^1.0.0",
    "vinyl-source-stream": "^1.1.0"
  },
  "dependencies": {
    "babel-runtime": "^6.18.0"
  }
}

• name：默认为作者名字，除非在git目录中，它会是git仓库的名字；
• version：版本号，刚初始化的项目总是1.0.0；
• main：项目启动的名字，这个项目没有设置;
• scripts：项目测试路径；
• author：作者
• license：ISC开源证书
• repository: github版本控制路径

指定依赖包

• “dependencies”: 在项目中所需要的安装包
• “devDependencies”: 只在项目开发中需要的安装包

添加package.json依赖的入口(dependencies)：

npm install <package_name> --save

添加package.json开发环境依赖的入口(devDependencies)：

npm install <package_name> --save-dev

scripts字段

• scripts指定了运行脚本命令的npm命令行缩写，比如start指定了运行npm run start时，所要执行的命令。

• 下面的设置指定了npm run preinstall、npm run postinstall、npm run start、npm run test时，所要执行的命令。

"scripts": {
    "preinstall": "echo here it comes!",
    "postinstall": "echo there it goes!",
    "start": "node index.js",
    "test": "tap test/*.js"
}

查看本地包是否有新版本

npm outdated

更新本地包

npm update

卸载本地包

通过npm uninstall <package>命令，你可以将node_modules目录下的某个依赖包移除：

npm uninstall babel-core

从package.json文件的依赖列表中移除，需要使用--save标签：

npm uninstall --save babel-core