HTMLOptionsCollection: add() method
The add() method of the HTMLOptionsCollection interface adds an HTMLOptionElement or HTMLOptGroupElement to this HTMLOptionsCollection.
Syntax
add(item)
add(item, before)
Parameters
itembeforeOptionalAn element of the collection, or a numeric 0-based index representing the element that the
itemshould be inserted before. If omitted,null, or the index does not exist, the new element is appended to the end of the collection.
Return value
None (undefined).
Exceptions
HierarchyRequestErrorDOMExceptionThrown if the
itempassed to the method is an ancestor of the element into which it is to be inserted.
Description
By default, the add() appends the <option> or <optgroup> passed as the parameter to the end of the collection. You can define where the added <option> or <optgroup> should be placed by specifying the before parameter. The before is the <option> element or a numeric 0-based index of the <option> element the added element should precede.
If the before parameter is null or out of range (or omitted), the <option> or <optgroup> will be appended as the last element in the collection, outside of any <optgroup>. If the <option> referenced by the before parameter is in an <optgroup>, an added HTMLOptionElement will be in the same group.
The <optgroup> element can only contain <option> elements as child nodes. The add() method will successfully add an HTMLOptGroupElement to the end of the HTMLOptionsCollection or between <optgroup> elements only. In other words, attempting to add an HTMLOptGroupElement before an <option> within an <optgroup> may silently fail if the <option> referenced by the before parameter is not the first <option> within its <optgroup>.
Examples
const optionList = document.querySelector("select").options;
const firstOption = document.createElement("option");
firstOption.text = "new item";
optionList.add(firstOption, 0); // added as the first item
optionList.add(optionList[0]); // moves the first item to the end
Specifications
| Specification |
|---|
| HTML # dom-htmloptionscollection-add-dev |