JavaScript Array filter()

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Example 1

Return an array of all values in ages[] that are 18 or over:

const ages = [32, 33, 16, 40];
const result = ages.filter(checkAdult);

function checkAdult(age) {
return age >= 18;
}

Try it Yourself »

Definition and Usage

The filter() method creates a new array filled with elements that pass a test provided by a function.

The filter() method does not execute the function for empty elements.

The filter() method does not change the original array.

Syntax

array.filter(function(currentValue, index, arr), thisValue)

Parameters

Parameter	Description
function()	Required. A function to run for each array element.
currentValue	Required. The value of the current element.
index	Optional. The index of the current element.
arr	Optional. The array of the current element.
thisValue	Optional. Default `undefined` A value passed to the function as its `this` value.

Return Value

Type	Description
An array	Containing the elements that pass the test. If no elements pass the test it returns an empty array.

Example 2

Return the values in ages[] that are over a specific number:

<p><input type="number" id="ageToCheck" value="30"></p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
const ages = [32, 33, 12, 40];

function checkAge(age) {
return age > document.getElementById("ageToCheck").value;
}

function myFunction() {
document.getElementById("demo").innerHTML = ages.filter(checkAge);
}
</script>