.every()

The .every() method iterates over each element in an array and stops when a falsy value is returned by the provided callback function. If a falsy value is found, .every() returns false. Otherwise, the function will return true.

Syntax

array.every(callbackFn);

array.every(callbackFn, thisArg);

The .every() method needs an argument callbackFn, which is a callback function executed on each element in the list. There can be a second argument thisArg, which is optional and is needed in special cases.

The callbackFn function can contain up to three arguments, which are:

• element: The element being processed in the current iteration.
• index: The position of the current element inside of the array.
• array: The current array, processed by the .every() method.

Examples

Check if all words in the array have more than 3 characters:

const words = ['apple', 'banana', 'cherry', 'date'];
const allLongWords = words.every((word) => word.length > 3);

console.log(allLongWords);

This example results in the following output:

true

Verify whether every element in the array is defined :

const arr = [5, 9, , 29, 57, 1];
console.log(arr.every((i) => i !== undefined));

This example results in the following output:

true

Note: .every() does not read empty slots.

Codebyte Example

The following example checks if all numbers in the array are even:

const numbers = [2, 4, 6, 8, 10];
const allEven = numbers.every((number) => number % 2 === 0);

console.log(allEven);