node.js TypeError：路径必须是绝对路径，或为res.sendFile指定根目录[无法解析JSON]

问题描述

错误非常明显，您需要指定一个绝对路径（而不是相对路径）和/或root在的config对象中设置res.sendFile()。例子：

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

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

或指定一个根（用作第一个参数的基本路径res.sendFile()：

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

root当您传递用户生成的文件路径时，指定路径可能会更有用，该文件路径可能包含格式不正确/恶意的部分..（例如../../../../../../etc/passwd）。设置root路径可防止此类恶意路径用于访问该基本路径之外的文件。

解决方法

[添加]所以我的下一个问题是，当我尝试添加新的依赖项时（npm install –save
socket.io）。JSON文件也有效。我收到此错误：无法解析json

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

因此，我一直在尝试找出为什么此错误一直在返回。所有文件（HTML，JSON，JS）都在我桌面上的同一文件夹内。我正在使用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)