Давайте проверим еще несколько случаев:
function getFirstAndLastFrom( URL ){
const a = document.createElement("a");
a.href = URL;
let pathname = a.pathname.split("/");
pathname.shift(); // Filter out first entry
pathname.pop(); // Filter out last entry
const first = pathname.length > 0 ? pathname[0] : null; // Do we have a first element?
const last = pathname.length > 1 ? pathname[pathname.length-1] : null; // Do we have a last element?
return { first, last };
}
const URL1 = "http://www.example.com/folder-1/folder-2/folder-3/index.html";
const URL2 = "http://example.com/folder-1/folder-2/folder-3/";
const URL3 = "http://www.example.com";
const URL4 = "http://subdomain.example.com/folder-1/folder-2/image.jpg";
const URL5 = "http://www.example.com/folder-1/image.jpg";
const URL6 = "http://www.google.com/";
{
// Test case #1
let { first, last } = getFirstAndLastFrom( URL1 );
console.log( URL1, first, last );
}
{
// Test case #2
let { first, last } = getFirstAndLastFrom( URL2 );
console.log( URL2, first, last );
}
{
// Test case #3
let { first, last } = getFirstAndLastFrom( URL3 );
console.log( URL3, first, last );
}
{
// Test case #4
let { first, last } = getFirstAndLastFrom( URL4 );
console.log( URL4, first, last );
}
{
// Test case #5
let { first, last } = getFirstAndLastFrom( URL5 );
console.log( URL5, first, last );
}
{
// Test case #6
let { first, last } = getFirstAndLastFrom( URL6 );
console.log( URL6, first, last );
}