HTMLOptionsCollection: length property

The length property of the HTMLOptionsCollection interface returns the number of <option> elements in the collection. The property can get or set the size of the collection.

When setting length to a value smaller than the current, the options collection gets truncated; otherwise, new blank <option> elements are appended to the end of the <select>.

const optCollection = document.getElementById("fruits").options;
const origLength = optCollection.length;
optCollection.length += 50; // adds 50 blank options to the collection
optCollection.length = origLength; // truncates the list back to the original size