node.jsTypeError：路径必须是绝对的或指定根res.send文件[未能解析JSON]

Question

[add]所以我的下一个问题是，当我尝试添加一个新的依赖项时（npm安装--save socket.io）。JSON文件也是有效的。我得到这个错误：解析json失败

npm ERR! Unexpected string
npm ERR! File: /Users/John/package.json
npm ERR! Failed to parse package.json data.
npm ERR! package.json must be actual JSON, not just JavaScript.
npm ERR! 
npm ERR! This is not a bug in npm.
npm ERR! Tell the package author to fix their package.json file. JSON.parse 

所以我一直在试图弄清楚为什么这个错误会返回。所有文件（超文本标记语言、JSON、JS）都在我桌面上的同一个文件夹中。我用node.js和socket.io

这是我的JS文件：

var app = require('express')();
var http = require('http').Server(app);

app.get('/', function(req, res){
  res.sendFile('index.html');
});

http.listen(3000,function(){
    console.log('listening on : 3000');
});

这就是返回的内容：

MacBook-Pro:~ John$ node /Users/John/Desktop/Chatapp/index.js 
listening on : 3000
TypeError: path must be absolute or specify root to res.sendFile
    at ServerResponse.sendFile (/Users/John/node_modules/express/lib/response.js:389:11)
    at /Users/John/Desktop/Chatapp/index.js:5:7
    at Layer.handle [as handle_request] (/Users/John/node_modules/express/lib/router/layer.js:76:5)
    at next (/Users/John/node_modules/express/lib/router/route.js:100:13)
    at Route.dispatch (/Users/John/node_modules/express/lib/router/route.js:81:3)
    at Layer.handle [as handle_request] (/Users/John/node_modules/express/lib/router/layer.js:76:5)
    at /Users/John/node_modules/express/lib/router/index.js:234:24
    at Function.proto.process_params (/Users/John/node_modules/express/lib/router/index.js:312:12)
    at /Users/John/node_modules/express/lib/router/index.js:228:12
    at Function.match_layer (/Users/John/node_modules/express/lib/router/index.js:295:3)
TypeError: path must be absolute or specify root to res.sendFile
    at ServerResponse.sendFile (/Users/John/node_modules/express/lib/response.js:389:11)
    at /Users/John/Desktop/Chatapp/index.js:5:7
    at Layer.handle [as handle_request] (/Users/John/node_modules/express/lib/router/layer.js:76:5)
    at next (/Users/John/node_modules/express/lib/router/route.js:100:13)
    at Route.dispatch (/Users/John/node_modules/express/lib/router/route.js:81:3)
    at Layer.handle [as handle_request] (/Users/John/node_modules/express/lib/router/layer.js:76:5)
    at /Users/John/node_modules/express/lib/router/index.js:234:24
    at Function.proto.process_params (/Users/John/node_modules/express/lib/router/index.js:312:12)
    at /Users/John/node_modules/express/lib/router/index.js:228:12
    at Function.match_layer (/Users/John/node_modules/express/lib/router/index.js:295:3)

Answer 1

尝试添加根路径。

app.get('/', function(req, res) {
    res.sendFile('index.html', { root: __dirname });
});

Answer 2

在里面mjs文件我们现在没有_udirname

因此

res.sendFile('index.html', { root: '.' })

Answer 3

错误很明显，您需要在res.sendFile（）的配置对象中指定绝对（而不是相对）路径和/或设置root。示例：

// assuming index.html is in the same directory as this script

res.sendFile(__dirname + '/index.html');

或者指定根目录（用作res.sendFile（）的第一个参数的基本路径）：

res.sendFile('index.html', { root: __dirname });

指定root路径在传递用户生成的文件路径时更有用，该路径可能包含格式错误/恶意的部分，如...（例如./.../.../.../.../.../etc/Passwd）。设置root路径可防止此类恶意路径被用于访问该基路径之外的文件。