npm ERR!     at Object.parse (native)npm ERR!     at RegClient.
    
      (/usr/local/node/lib/node_modules/npm/node_                                                                                       modules/npm-registry-client/lib/request.js:266:23)npm ERR!     at Request._callback (/usr/local/node/lib/node_modules/npm/node_modu                                                                                       les/npm-registry-client/lib/request.js:238:65)npm ERR!     at Request.self.callback (/usr/local/node/lib/node_modules/npm/node_                                                                                       modules/request/request.js:123:22)npm ERR!     at Request.emit (events.js:98:17)npm ERR!     at Request.
     
       (/usr/local/node/lib/node_modules/npm/node_m                                                                                        dules/request/request.js:893:14)npm ERR!     at Request.emit (events.js:117:20)npm ERR!     at IncomingMessage.
      
        (/usr/local/node/lib/node_modules/np                                                                                        /node_modules/request/request.js:844:12)npm ERR!     at IncomingMessage.emit (events.js:117:20)npm ERR!     at _stream_readable.js:938:16npm ERR! If you need help, you may report this *entire* log,npm ERR! including the npm and node versions, at:npm ERR!     
       
        npm ERR! System Linux 2.6.32-358.el6.i686npm ERR! command "/usr/local/node/bin/node" "/usr/local/node/bin/npm" "install"                                                                                         -g" "express"npm ERR! cwd /root/node/my-projectnpm ERR! node -v v0.10.30npm ERR! npm -v 1.4.21npm ERR! type unexpected_eosnpm ERR!npm ERR! Additional logging details can be found in:npm ERR!     /root/node/my-project/npm-debug.lognpm ERR! not ok code 0[root@myfreax my-project]# npm install -g expressnpm ERR! registry error parsing jsonnpm ERR! 404 404 Not Found: expressnpmnpm ERR! 404npm ERR! 404 'expressnpm' is not in the npm registry.npm ERR! 404 You should bug the author to publish itnpm ERR! 404npm ERR! 404 Note that you can also install from anpm ERR! 404 tarball, folder, or http url, or git url.npm ERR! System Linux 2.6.32-358.el6.i686npm ERR! command "/usr/local/node/bin/node" "/usr/local/node/bin/npm" "install" "-g" "expressnpm" "ERR!" "registry" "error" "parsing" "json"npm ERR! cwd /root/node/my-projectnpm ERR! node -v v0.10.30npm ERR! npm -v 1.4.21npm ERR! code E404npm ERR!npm ERR! Additional logging details can be found in:npm ERR!     /root/node/my-project/npm-debug.lognpm ERR! not ok code 0
       
      
     
    

看后面那么多404想必是因为网络引起，安装出错，于是于是去查了一下，原来npm，也像Linux的软件一样有自己的镜像源，感觉不错，虽然也存在依赖关系，非常不错、

下面就是切换npm镜像源的方法有三种：

1.通过config命令

npm config set registry https://registry.npm.taobao.org  npm info underscore （如果上面配置正确这个命令会有字符串response）

2.命令行指定

npm --registry https://registry.npm.taobao.org info underscore

3.编辑~/.npmrc加入下面内容

registry = https://registry.npm.taobao.org