Undefined value returned - Javascript

Question

I am receiving a value from a function to pass to a method in a class. When I pass the value returned from the function in web.js, it returns undefined in my shopifyStore class. What could be the reason and how I could solve this ?

PS: Beginner with javascript

web.js

window.shopify.findName({}, function(items) {  
   var shopify = items;

   console.log(items); //this returns the value 
   pushValue(items); 
});

export function pushValue(items) { return items; }

component

import * as shopifyHelper from '/web.js';

class shopifyStore extends HTMLElement {
   constructor() {
      super();
   }

   getItemCount() {
      console.log(shopifyHelper.pushValue()) // this returns undefined
   }
}

Try export default pushValue; And import it as import { pushValue } from './web.js'; — Trishant Pahwa
– Trishant Pahwa, Commented Nov 11, 2020 at 9:40
@TrishantPahwa, can you explain how different your answer is, please ? — Switz
– Switz, Commented Nov 11, 2020 at 9:44
I guess the way your are exporting and importing the function is incorrect. — Trishant Pahwa
– Trishant Pahwa, Commented Nov 11, 2020 at 9:46

Maksym Bezruchko · Accepted Answer · 2020-11-11 10:09:07Z

2

You should promisify the callback of window.shopify.findName method. Rework your pushValue function:

export function pushValue(items) {
   return new Promise((resolve, reject) => {
      window.shopify.findName({}, items => resolve(items));
   })
}

and call it like this:

async getItemCount() {
   console.log(await shopifyHelper.pushValue());
}

or:

getItemCount() {
   shopifyHelper.pushValue().then(items => console.log(items));
}

Here you can read more about async functions. And here you can read more about promises.

edited Nov 11, 2020 at 10:09

answered Nov 11, 2020 at 9:39

Maksym Bezruchko

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3 Comments

Switz Over a year ago

That was only a typo:). It actually returns undefined because the value is not ready yet. (callback).

Switz Over a year ago

You have any help ? I am just starting with JS

Switz Over a year ago

Thanks. you are the best

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