I call an Api. When I run the code , it returns some error like :

.js

let new_case = document.getElementById('new_case');
let new_case_excludeabroad = document.getElementById('new_case_excludeabroad');
let new_death = document.getElementById('new_death');
let new_recovered = document.getElementById('new_recovered');
let total_case = document.getElementById('total_case');
let total_case_excludeabroad = document.getElementById('total_case_excludeabroad');
let total_death = document.getElementById('total_death');
let total_recovered = document.getElementById('total_recovered');
let txn_date = document.getElementById('txn_date');

fetch('https://covid19.ddc.moph.go.th/api/Cases/today-cases-all')

.then(response => response.json().then(data => 
{
    console.log(data);

    new_case.innerHTML = data[0].new_case.toLocaleString();
    new_case_excludeabroad.innerHTML = data[0].new_case_excludeabroad.toLocaleString();
    new_death.innerHTML = data[0].new_death.toLocaleString();
    new_recovered.innerHTML = data[0].new_recovered.toLocaleString();
    total_case.innerHTML = data[0].total_case.toLocaleString();
    total_case_excludeabroad.innerHTML = data[0].total_case_excludeabroad.toLocaleString();
    total_death.innerHTML = data[0].total_death.toLocaleString();
    total_recovered.innerHTML = data[0].total_recovered.toLocaleString();
    txn_date.innerHTML = data[0].txn_date.toLocaleString();
}))

.catch(err => 
{
    console.log(err);    
});

Error:

Access to fetch at 'https://covid19.ddc.moph.go.th/api/Cases/today-cases-all' from origin 'http://127.0.0.1:5000' 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.

Access to XMLHttpRequest at 'https://covid19.ddc.moph.go.th/api/Cases/today-cases-all' from origin 'http://127.0.0.1:5000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

What should I do?

Where do I add the code and how do I do it?