Using Node.js I get readFileSync is not a function - angularjs

Question

I am developing a web app with Angular 2, typescript, nodejs and Visual Studio. I want to read a file located in my wwwroot folder. so far I have created the following class:
///<reference path="../../node_modules/angular2/ts/typings/node/node.d.ts"/>
export class LoadConfigurationService {
fs: any;
constructor() {
this.fs = require('fs');
let data = this.fs.readFileSync('input.txt');
}
}
The problem is that I always get the error "readFileSync is not a function". I have tried to install the node file system module by adding the following line
"file-system": "^2.2.1"
to my package.json dependencies. I've also added
"node.TypeScript.DefinitelyTyped": "2.8.8"
to my project.json dependencies. But it keeps giving me the same error. What am I doing wrong?

Answer 1

Your code works for me, such as it is. What error are you getting? Here's the (slightly amended) ts:
declare var require: any;
export class LoadConfigurationService {
fs: any;
public data: string;
constructor() {
this.fs = require('fs');
this.data = this.fs.readFileSync('input.txt').toString();
}
}
const obj = new LoadConfigurationService();
console.log(obj.data);
Run this through tsc v1.8.7 produces:
"use strict";
var LoadConfigurationService = (function () {
function LoadConfigurationService() {
this.fs = require('fs');
this.data = this.fs.readFileSync('input.txt').toString();
}
return LoadConfigurationService;
}());
exports.LoadConfigurationService = LoadConfigurationService;
var obj = new LoadConfigurationService();
console.log(obj.data);
Run this with a suitable input.txt (consisting of "File Contents", for me) in the local directory and get:
$ node temp.js
File Contents
Possible problems
There are a couple issues I can see that might get in your way.
The code depends on the native node fs, not "file-system": "^2.2.1"
The worth of the referenced npmjs library aside, you are invoking the native fs library.
Don't require a dependency inside a constructor.
Dependencies for objects is a problem and worth reading about, but this is not a good way to handle it. fs should be immutable, so there's no advantage to requiring it each time the object is constructed. Just one line at the top of the file will do:
const fs = require('fs');
fs inside Angular?
I'm not sure what the snippet has to do with Angular, but if this code is getting webpacked or browserified things will become difficult. fs is for file system access and bundling that into the browser will not end well.