[Home](./index.md) > [rc-js-util](./rc-js-util.md) > [\_Map](./rc-js-util._map.md) > [concat](./rc-js-util._map.concat.md) ## \_Map.concat property Used with maps that store arrays. Where an array exists for a given key the values will be appended to that array, otherwise a copy of values array will be inserted. **Signature:** ```typescript static readonly concat: typeof mapConcat; ``` ## Remarks See [mapConcat()](./rc-js-util.mapconcat.md).