Add basis for exercise as well as task description

js/currency.js

@@ -0,0 +1,20 @@
+const currency = new URLSearchParams(window.location.search).get("currency");
+const countryList = document.getElementById("country-list");
+fetch("https://countries.trevorblades.com/", {
+    "method": "POST",
+    "body": JSON.stringify(
+        {
+            query: "", // Fill in Query here
+            "operationName": "countriesPayingIn",
+            "variables": { "currency": currency }
+        }),
+    headers: { "Content-Type": "application/json" }
+}).then(response => response.json()).then(({ data }) => {
+    document.getElementById("currency").innerText = currency;
+    const countries = data.countries;
+    for (const country of countries) {
+        const newListItem = document.createElement("li");
+        newListItem.innerHTML = `<a href="/country.html?code=${country.code}"> ${country.name} </a>`;
+        countryList.append(newListItem);
+    }
+});