JavaScript - Schleifen

const items = ['item1', 'item2', 'item3'];
const copy = [];

// klassisch
for (let i=0; i<items.length; i++) {
  copy.push(items[i]);
}

https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach

// each
items.forEach(function(item){
  copy.push(item);
});