# `AggregationsScriptedMetricAggregation` [interface-AggregationsScriptedMetricAggregation]

| Name | Type | Description |
| - | - | - |
| `combine_script` | [Script](./Script.md) | [ScriptSource](./ScriptSource.md) | Runs once on each shard after document collection is complete. Allows the aggregation to consolidate the state returned from each shard. |
| `init_script` | [Script](./Script.md) | [ScriptSource](./ScriptSource.md) | Runs prior to any collection of documents. Allows the aggregation to set up any initial state. |
| `map_script` | [Script](./Script.md) | [ScriptSource](./ScriptSource.md) | Run once per document collected. If no `combine_script` is specified, the resulting state needs to be stored in the `state` object. |
| `params` | Record<string, any> | A global object with script parameters for `init`, `map` and `combine` scripts. It is shared between the scripts. |
| `reduce_script` | [Script](./Script.md) | [ScriptSource](./ScriptSource.md) | Runs once on the coordinating node after all shards have returned their results. The script is provided with access to a variable `states`, which is an array of the result of the `combine_script` on each shard. |