Using Javascript object in seperate file

Question

I'm using Nativescript-vue. I'm trying to put some logic in my app, that doesn't show any html or anything, its just a library that does calculations. I can't figure out how to just use it, i keep getting error messages.

Here is what I've tried.

rifle.js

 export function Rifle () { // no function name
   this.firstName = "hi";
  }

also tried this and others:

const observableModule = require("tns-core-modules/data/observable");


function Rifle () { // no function name
   const myRifle = observableModule.fromObject({
        firstName:"hello"
   })

   return myRifle;
  }

  module.exports = Rifle;

then in my App.js file, i import it.

import {Rifle} from "./ballisticlibrary/rifle";

I've also tried to use Require instead.

I then try to use it in a vue method, invoked on button tap.

  GetRifle()
  {
     // return "hi";
   this.msg= this.Rifle.firstName;

  }

Keeps throwing an error of :

Cannot read property 'firstName' of undefined"
System.err: An uncaught Exception occurred on "main" thread.
System.err: Calling js method onClick failed
System.err: TypeError: Cannot read property 'firstName' of undefined

I have never used vue but i would expect the exported Rifle value to be a function or a class. That would suggest that you need to first create an instance of that class before using it. Also, i think that you cant access the imported classes using "this". you can try . const rifle = new Rifle(); this.msg = rifle.firstName; — Rainer Plumer
– Rainer Plumer, Commented Feb 1, 2020 at 15:07
@RainerPlumer this worked, export function Rifle () { // no function name this.firstName= "hi"; function GetHelp (){ return "Help" } } Do you know why my function GetHelp wouldn't work though? — Dylan
– Dylan, Commented Feb 1, 2020 at 15:26

Rainer Plumer · Accepted Answer · 2020-02-01 15:43:56Z

2

moved a comment into an answer for better formatting *

I have never used vue but I would expect the exported Rifle value to be a function or a class. That would suggest that you need to first create an instance of that class before using it. Also, I think that you cant access the imported classes using "this". you can try.

// your rifle class
export function Rifle () {
    this.name = "AK-47";
    this.damage = 5;
    this.fire = () => {
        console.log('Bang bang, '+ this.damage + ' damage done by ' + this.name);
    }
}

// then import your rifle and instantiate it

const ak = new Rifle();
ak.fire();

// logs out Bang bang, 5 damage done by AK-47

answered Feb 1, 2020 at 15:43

Rainer Plumer

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1 Comment

Dylan Over a year ago

Thanks a lot. I've been struggling to get this to work like this for awhile, and this did it.

Johnny Zabala · Accepted Answer · 2020-02-01 15:10:14Z

0

The problem here is this.firstName. Read this to better understand how to use this in js.

answered Feb 1, 2020 at 15:10

Johnny Zabala

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