Problem with moving functions from one file to another file via export and import

Question

Problem with moving functions from one file to another file via export and import

I currently have the following file structure:

---utilities
-----index.ts
-----tools.ts
allfunctions.ts

Within the tools.ts file, I have defined several functions that I export using export const. One of them is the helloWorld function:

export const helloWorld = () => console.log('Hello World');

In the utilities/index.ts file, I've imported the tools file and exported it like this:

import * as toolsFunction from './tools';

export { toolsFunction }

Now in my allfunctions.ts file, I am trying to use the helloWorld function in the following way:

import { taskFunctions as Utility } from './utilities/';

taskFunctions.helloWorld();

Before compiling the code, everything works fine. However, when I try to compile, I encounter the following error message:

TypeError: Cannot read property 'helloWorld' of undefined

I'm not sure what mistake I might be making here. Could you provide some insight?

typescript

Answer 1

Answer №1

When using typescript's import to bring in a module, the syntax is as follows:

import * as myModule from './superModule'
myModule.doStuff()

or

import {doStuff} from './superModule'
doStuff()

or

import {doStuff as superFunction} from './superModule'
superFunction()

In this case, the issue arises because taskFunctions is not defined, and you should instead call your helloWorld function using Utility. Try :

import { toolsFunctions as Utility } from './utilities/';

Utility.helloWorld();

For further details, refer to https://www.typescriptlang.org/docs/handbook/modules.html

Answer 2

When using typescript's import to bring in a module, the syntax is as follows:

import * as myModule from './superModule'
myModule.doStuff()

or

import {doStuff} from './superModule'
doStuff()

or

import {doStuff as superFunction} from './superModule'
superFunction()

In this case, the issue arises because taskFunctions is not defined, and you should instead call your helloWorld function using Utility. Try :

import { toolsFunctions as Utility } from './utilities/';

Utility.helloWorld();

For further details, refer to https://www.typescriptlang.org/docs/handbook/modules.html

Answer 3

Answer №2

The reason for the issue is that you are not correctly invoking the helloWorld() function. The function is exported as toolsFunction, but you are trying to import it as taskFunctions in your allfunctions.ts. Additionally, you need to call the function using the new alias Utility. Your code should be updated as follows:

tools.ts

export const helloWorld = () => console.log('Hello World');

index.ts

import * as toolsFunction from './tools';

export { toolsFunction }

allfunctions.ts

import {toolsFunction as Utility} from './utilities/'

export {Utility};

usage in app.component.ts

import { Component } from '@angular/core';
import {Utility} from './allfunctions'

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  name = 'Angular 4';

  constructor(){
    Utility.helloWorld();
  }
}

For a working demonstration, visit: https://stackblitz.com/edit/angular4-zzhcu5

Answer 4

The reason for the issue is that you are not correctly invoking the helloWorld() function. The function is exported as toolsFunction, but you are trying to import it as taskFunctions in your allfunctions.ts. Additionally, you need to call the function using the new alias Utility. Your code should be updated as follows:

tools.ts

export const helloWorld = () => console.log('Hello World');

index.ts

import * as toolsFunction from './tools';

export { toolsFunction }

allfunctions.ts

import {toolsFunction as Utility} from './utilities/'

export {Utility};

usage in app.component.ts

import { Component } from '@angular/core';
import {Utility} from './allfunctions'

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  name = 'Angular 4';

  constructor(){
    Utility.helloWorld();
  }
}

For a working demonstration, visit: https://stackblitz.com/edit/angular4-zzhcu5

Problem with moving functions from one file to another file via export and import

Answer №1

Answer №2

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