regex для строки js

const regex = /(?<=post=)\d+/gm;
const str = `http://skolerom.loc/wp-admin/admin.php?action=duplicate_post_save_as_new_post&post=16011&_wpnonce=bc80ec66ff
/wp-admin/admin.php?action=duplicate_post_save_as_new_post&post=16011&_wpnonce=bc80ec66ff`;
let m;

while ((m = regex.exec(str)) !== null) {
    // This is necessary to avoid infinite loops with zero-width matches
    if (m.index === regex.lastIndex) {
        regex.lastIndex++;
    }
    
    // The result can be accessed through the `m`-variable.
    m.forEach((match, groupIndex) => {
        console.log(`Found match, group ${groupIndex}: ${match}`);
    });
}

const regexp = /&post=[\d]+/;

const str = 'http://skolerom.loc/wp-admin/admin.php?action=duplicate_post_save_as_new_post&post=16011&_wpnonce=bc80ec66ff';

let resultId = str.match(regexp)[0].match(/\d+/)[0];

console.log(resultId);