---
title: contains() function
description: >
  `contains()` tests if an array contains a specified value and returns `true` or `false`.
menu:
  flux_0_x_ref:
    name: contains
    parent: universe
    identifier: universe/contains
weight: 101

introduced: 0.19.0
---

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`contains()` tests if an array contains a specified value and returns `true` or `false`.



##### Function type signature

```js
(set: [A], value: A) => bool where A: Nullable
```

{{% caption %}}For more information, see [Function type signatures](/flux/v0.x/function-type-signatures/).{{% /caption %}}

## Parameters

### value
({{< req >}})
Value to search for.



### set
({{< req >}})
Array to search.




## Examples

### Filter on a set of specific fields

```js
fields = ["f1", "f2"]

data
    |> filter(fn: (r) => contains(value: r._field, set: fields))

```

{{< expand-wrapper >}}
{{% expand "View example input and ouput" %}}

#### Input data

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f1      | m             | 2021-01-01T00:00:00Z | -2      | t1   |
| f1      | m             | 2021-01-01T00:00:50Z | 4       | t1   |

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f1      | m             | 2021-01-01T00:00:10Z | 4       | t2   |
| f1      | m             | 2021-01-01T00:00:20Z | -3      | t2   |
| f1      | m             | 2021-01-01T00:00:50Z | 1       | t2   |

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f2      | m             | 2021-01-01T00:00:10Z | 10      | t1   |
| f2      | m             | 2021-01-01T00:00:20Z | 7       | t1   |

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f3      | m             | 2021-01-01T00:00:30Z | 17      | t1   |
| f3      | m             | 2021-01-01T00:00:40Z | 15      | t1   |

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f3      | m             | 2021-01-01T00:00:00Z | 19      | t2   |
| f3      | m             | 2021-01-01T00:00:30Z | 19      | t2   |
| f3      | m             | 2021-01-01T00:00:40Z | 13      | t2   |


#### Output data

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f1      | m             | 2021-01-01T00:00:00Z | -2      | t1   |
| f1      | m             | 2021-01-01T00:00:50Z | 4       | t1   |

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f1      | m             | 2021-01-01T00:00:10Z | 4       | t2   |
| f1      | m             | 2021-01-01T00:00:20Z | -3      | t2   |
| f1      | m             | 2021-01-01T00:00:50Z | 1       | t2   |

| *_field | _measurement  | _time                | _value  | *tag |
| ------- | ------------- | -------------------- | ------- | ---- |
| f2      | m             | 2021-01-01T00:00:10Z | 10      | t1   |
| f2      | m             | 2021-01-01T00:00:20Z | 7       | t1   |

{{% /expand %}}
{{< /expand-wrapper >}}