>O</var> be the <emu-val>this</emu-val> value.</li><li>Perform ?&nbsp;RequireInternalSlot(<var>O</var>, <var class="field">[[SetData]]</var>).</li><li>If IsCallable(<var>callbackfn</var>) is <emu-val>false</emu-val>, throw a <emu-val>TypeError</emu-val> exception.</li><li>Let <var>resultSetData</var> be a new empty List.</li><li>Let <var>entries</var> be <var>O</var>.<var class="field">[[SetData]]</var></li><li>Let <var>thisSize</var> be the number of elements in <var>O</var>.<var class="field">[[SetData]]<