API Reference > bentleyjs-core > Collections > IndexMap > insert insert Method Attempt to insert a new value into the map. If an equivalent element already exists in the map, the corresponding index is returned. If the map is full, nothing is inserted and -1 is returned. Otherwise: The new element is mapped to the next-available index (that is, the length of the map prior to insertion of this new element); the value is cloned using the function supplied to the IndexMap constructor; the cloned result is inserted into the map; and the index of the new element is returned. insert(value: T, onInsert?: (value: T) => any): number Parameter Type Description value T The value to insert onInsert (value: T) => any The optional callback method to call if insertion occurs with the inserted value Returns - number the index of the equivalent element in the map, or -1 if the map is full and no equivalent element exists. Defined in core/bentley/src/IndexMap.ts Line 73 Last Updated: 11 June, 2024