Javascript 云9 NPM不再工作

我使用node express在cloud 9中测试web应用程序。npm app.js在突然停止工作之前正在工作。当我运行npm app.js时，返回下面的命令行：有什么想法吗

Usage: npm <command>

where <command> is one of:
    access, adduser, bin, bugs, c, cache, completion, config,
    ddp, dedupe, deprecate, dist-tag, docs, edit, explore, get,
    help, help-search, i, init, install, install-test, it, link,
    list, ln, login, logout, ls, outdated, owner, pack, ping,
    prefix, prune, publish, rb, rebuild, repo, restart, root,
    run, run-script, s, se, search, set, shrinkwrap, star,
    stars, start, stop, t, tag, team, test, tst, un, uninstall,
    unpublish, unstar, up, update, v, version, view, whoami

npm <cmd> -h     quick help on <cmd>
npm -l           display full usage info
npm help <term>  search for help on <term>
npm help npm     involved overview

Specify configs in the ini-formatted file:
    /home/ubuntu/.npmrc
or on the command line via: npm <command> --key value
Config info can be viewed via: npm help config

npm@3.10.10 /home/ubuntu/.nvm/versions/node/v6.11.3/lib/node_modules/npm

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npm是包管理器。你想运行node app.js吗？

是的。我运行了npm app.js，但它返回了命令行指令。它最初工作了2天，直到昨天晚上。看看我现在正在工作，我使用npm app.js而不是node app.js谢谢。