你可以用不同的方法定位父文件夹下的文件，

const path = require('path');
const fs = require('fs');

// reads foo.bar file which is located in immediate parent folder.
fs.readFile(path.join(__dirname, '..', 'foo.bar'); 

// Method 1: reads foo.bar file which is located in 2 level back of the current folder.
path.join(__dirname, '..','..');


// Method 2: reads foo.bar file which is located in 2 level back of the current folder.
fs.readFile(path.normalize(__dirname + "/../../foo.bar"));

// Method 3: reads foo.bar file which is located in 2 level back of the current folder.
fs.readFile(__dirname + '/../../foo.bar');

// Method 4: reads foo.bar file which is located in 2 level back of the current folder.
fs.readFile(path.resolve(__dirname, '..', '..','foo.bar'));

你可以使用

path.join(__dirname, '../..');

这很好

path.join(__dirname + '/../client/index.html')

const path = require('path')
const fs = require('fs')
    fs.readFile(path.join(__dirname + '/../client/index.html'))

使用路径。加入http://nodejs.org/docs/v0.4.10/api/path.html path.join

var path = require("path"),
    fs = require("fs");

fs.readFile(path.join(__dirname, '..', '..', 'foo.bar'));

Path.join()将为你处理开头/结尾斜杠，只是做正确的事情，你不必试图记住什么时候结尾斜杠存在，什么时候不存在。

这也可以:

fs.readFile(`${__dirname}/../../foo.bar`);

最简单的方法是使用path.resolve:

path.resolve(__dirname, '..', '..');