Array.prototype.every() - JavaScript

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Array instances tests whether all elements in the array pass the test implemented by the provided function. It returns a Boolean value.

Try it

const isBelowThreshold = (currentValue) => currentValue < 40; const array1 = [1, 30, 39, 29, 10, 13]; console.log(array1.every(isBelowThreshold)); / Expected output: true

Syntax

every(callbackFn)
every(callbackFn, thisArg)

Parameters

callbackFn: A function to execute for each element in the array. It should return a falsy value otherwise. The function is called with the following arguments:

element

The current element being processed in the array.

index

The index of the current element being processed in the array.

array

The array every() was called upon.
thisArg Optional: A value to use as this when executing callbackFn. See iterative methods.

Return value

true unless callbackFn returns a truthy value for all elements, every() returns true. Read the iterative methods section for more information about how these methods work in general.

every acts like the "for all" quantifier in mathematics. In particular, for an empty array, it returns true. (It is empty set satisfy any given condition.)

callbackFn is invoked only for array indexes which have assigned values. It is not invoked for empty slots in sparse arrays.

The every() method is generic. It only expects the this value to have a length property and integer-keyed properties.

Examples

Testing size of all array elements

The following example tests whether all elements in the array are 10 or bigger.

js
function isBigEnough(element, index, array) { return element >= 10; } [12, 5, 8, 130, 44].every(isBigEnough); / false [12, 54, 18, 130, 44].every(isBigEnough); / true

Check if one array is a subset of another array

The following example tests if all the elements of an array are present in another array.

js
const isSubset = (array1, array2) => array2.every((element) => array1.includes(element)); console.log(isSubset([1, 2, 3, 4, 5, 6, 7], [5, 7, 6])); / true console.log(isSubset([1, 2, 3, 4, 5, 6, 7], [5, 8, 7])); / false

Using the third argument of callbackFn

The array argument is useful if you want to access another element in the array. The following example first uses filter() to extract the positive values and then uses every() to check whether the array is strictly increasing.

js
const numbers = [-2, 4, -8, 16, -32]; const isIncreasing = numbers .filter((num) => num > 0) .every((num, idx, arr) => { / Without the arr argument, there's no way to easily access the / intermediate array without saving it to a variable. if (idx === 0) return true; return num > arr[idx - 1]; }); console.log(isIncreasing); / true

Using every() on sparse arrays

every() will not run its predicate on empty slots.

js
console.log([1, , 3].every((x) => x !== undefined)); / true console.log([2, , 2].every((x) => x === 2)); / true

Calling every() on non-array objects

The every() method reads the length property of this and then accesses each property with a nonnegative integer key less than length until they all have been accessed or callbackFn returns false.

js
const arrayLike = { length: 3, 0: "a", 1: "b", 2: "c", 3: 345, / ignored by every() since length is 3 }; console.log( Array.prototype.every.call(arrayLike, (x) => typeof x === "string"), ); / true

Specifications

Specification
ECMAScript® 2026 Language Specification # sec-array.prototype.every

Browser compatibility

See also

Polyfill of Array.prototype.every in core-js

es-shims polyfill of Array.prototype.every

Indexed collections guide

Array

Array.prototype.forEach()

Array.prototype.some()

Array.prototype.find()

TypedArray.prototype.every()

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