I have a Laravel application that uses Inertia and React as the front end. Recently I was getting a CORS error. Basically I was trying to use Shopify’s API to connect a user’s store and retrieve their products by using a Sales channel app I created. When I try to use axios.post from React to front end and then post to Shopify from there to receive access tokens and such I was always getting a CORS blocked because No access control header. This happened from the Shopify end as well when I tried to post from Shopify to my Laravel app using fetch.

But then when I finally tried using the approach below everything worked perfectly. Can someone please explain why? What’s the difference between using Axios or fetch and new Promise in this case?

let myPromise = new Promise((resolve, reject) => {
  resolve(url);
  reject("Error");
});

myPromise.then(
  function (result) {
    return ({
      success: true
    })
  },
  function (error) {
    console.error("ERROR::", error);
  },
);