No Access-Control-Allow-Origin header is present on the requested resource. set the request's mode to no-cors to fetch the resource with CORS disabled

Question

has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled

The URL downloading a txt file in web browser https://google.com/complete/search?client=chrome&q=python

import './App.css';
import {useState} from 'react';

function App() {
  const [Keyword, setKeyword] = useState("");
  const [Result, setResult] = useState([]);

  const findMatch = async () => {
    const getMatch = await fetch("http://google.com/complete/search?client=chrome&q=" + Keyword, {
      method: 'GET',
      headers: {
      'Access-Control-Allow-Origin': true,
      'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.102 Safari/537.36 Edge/18.19582',
      'Content-Type': 'text/plain',
      },
    })
    console.log(getMatch);
  }

  return (
    <div className="App">
      <input placeholder='Put Keyword' value={Keyword} onChange={(e) => setKeyword(e.target.value)} />
      <button onClick={findMatch}>Search</button>
    </div>
  );
}

export default App;

Answer 1

CORS is a server-side origin checking service where you can allow or disallow certain origins to request your resources. Given this, your header option 'Access-Control-Allow-Origin': true would be returned from the server in a RESPONSE header, while you're trying to put it in the REQUEST header and this will not work. You can try disabling CORS on your request, although this will allow for less headers in your request:

const getMatch = await fetch("http://google.com/complete/search?client=chrome&q=" + Keyword, {
      method: 'GET',
      mode: 'no-cors',
      headers: {
      'Content-Type': 'text/plain',
      },
    })

Source: https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#supplying_request_options