"this" reference is not working in nodeJs

Question

I have two methods in my nodeJs code like

function method1(id,callback){
  var data = method2();
  callback(null,data);
}

function method2(){
  return xxx;
}

module.exports.method1 = method1;
module.exports.method2 = method2;

for testing function method1 using Sinon and Mocha i had to stub method method2. For which it required to call method method2 as

function method1(id,callback){
      var data = this.method2();
      callback(null,data);
}

Test Code for this

describe('test method method2', function (id) {
    var id = 10;
    it('Should xxxx xxxx ',sinon.test(function(done){
       var stubmethod2 = this.stub(filex,"method2").returns(data);
       filex.method1(id,function(err,response){
         done();
       })
    })
})

using this test cases passed, But the code stopped working with error this.method2 is not a function.

Is there any way i can get rid of this or module.exports which seems buggy.

Please let me know if i missed any other info..

Answer 1

You are not using module.exports correctly.

Change your code to:

export function method1(id,callback){
  var data = method2();
  callback(null,data);
}

export function method2(){
  return xxx;
}

And then:

const MyFuncs = require('path_to_file_with_methods');

Where you need the methods, called like this:

MyFuncs.method1(){} MyFuncs.method2(){}

The docs for module.exports

You can also use module.exports in the following manner.

module.exports = {
    method1: method1,
    method2: method2
}

And require in the same fashion.

Edit:

Note that if your version supports it you can also a bit of syntactic sugar in your exports:

module.exports = {
    method1,
    method2
}

Which holds for object literal notation in general.

Answer 2

use arrow function to correct this method

in your case

function method1(id,callback){
  var data = this.method2();
  callback(null,data);
}

can be changed to

  let method1 = (id,callback)=>{
    var data = this.method2();
    callback(null,data);
  }