# on-change parameter (skin)

Source: https://ref.dm-lang.org/skin/param/on-change

### Applies to
> [Bar](https://ref.dm-lang.org/skin/control/bar.md)

### Format
> `string`

[Command](https://ref.dm-lang.org/skin/commands/index.md) executed when the [value](https://ref.dm-lang.org/skin/param/value.md) of the bar/slider is changed. If you drag the slider around, the command will not run until you let go.

If you include `[[*]]` in the command, it will be replaced by the control's new `value`. (See [embedded winget](https://ref.dm-lang.org/skin/commands/embed.md) for more details on the `[[...]]` format.)

### See also
> [value parameter](https://ref.dm-lang.org/skin/param/value.md)