array.where()

This method operates on an array. You typically fetch documents from a collection as a set, not an Array. For the equivalent Set method, see set instance methods.

For differences between Sets and Arrays, see Sets vs. Arrays.

Get a subarray of matching Array values.

Signature

where (predicate: (element: T) => Boolean | Null) => Array<T>

Description

The filter() method calls the predicate Function with each Array element as a parameter. The Array elements are passed as a parameter, sequentially, to predicate. The method creates an Array that consists of the Array elements for which the function calls evaluate to true.

If where() is the last value in a query, the first page of the created Array is returned.

the calling Array isn’t changed.

Parameters

Parameter Type Required Description

predicate

Function

Yes

Function to apply to each element of the calling Array. The predicate parameter must reference a boolean Function that evaluate to true or false when applied to the element parameter, or Null.

predicate parameters:

Parameter Type Required Description

element

Any

Array element to evaluate.

Return value

Type Description

Array

Array of elements that evaluate to true when the predicate function is applied to the calling array. If no predicate calls evaluate to true, the method returns an empty Array.

Examples

[1, 2, 3, 4].where(v => v > 2)
[
  3,
  4
]

See also

array.filter()

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