JavaScript Array every() Method

What You’ll Learn

The every() method checks whether all elements in an array satisfy a condition you define in a callback. It returns a boolean and stops as soon as one element fails. This tutorial covers syntax, five examples, empty-array behavior, and how it compares to some() and filter().

Introduction

When validating data, you often need a single yes/no answer: do all items meet a rule? The every() method is built for that question. Pass a test function; if every element passes, you get true.

Unlike filter(), which returns matching elements, or map(), which transforms them, every() only tells you whether the whole array satisfies your condition.

Understanding the every() Method

array.every(callback) walks the array from index 0 upward. For each element it calls your callback with (element, index, array). If the callback returns a falsy value for any element, every() immediately returns false without checking the rest.

If every callback returns a truthy value, the final result is true.

📝 Syntax

General form of Array.prototype.every:

array.every(callback(element, index, array), thisArg)

Parameters

• callback — function invoked per element. Should return a boolean (or truthy/falsy).
• element — current array item.
• index — optional; position of the element.
• array — optional; the array being traversed.
• thisArg — optional; value to use as this inside the callback.

Return value

• true if the callback is truthy for every element (including empty arrays).
• false as soon as any element fails the test.
• The original array is not modified by every() itself.

Common patterns

• nums.every(n => n > 0) — all positive?
• users.every(u => u.active) — all active accounts?
• fields.every(f => f.trim() !== "") — no empty form fields?

Examples Gallery

Open DevTools Console (F12) or use Try-it labs. Example N maps to ?tryit=N.

const numbers = [2, 4, 6, 8, 10];

const allEven = numbers.every((num) => num % 2 === 0);

console.log(allEven);
// true

true

const numbers = [2, 4, 6, 8, 10];

const allGreaterThanTen = numbers.every((num) => num > 10);

console.log(allGreaterThanTen);
// false

false

const empty = [];

const result = empty.every((n) => n > 0);

console.log(result);
// true

true

const students = [
  { name: "Alice", age: 22 },
  { name: "Bob", age: 25 },
  { name: "Charlie", age: 20 }
];

const allAdults = students.every((student) => student.age >= 18);

console.log(allAdults);
// true

true

const fields = ["John", "Doe", "john.doe@example.com"];

const allFilled = fields.every((value) => value.trim() !== "");

console.log(allFilled);
// true

const incomplete = ["John", "  ", "john.doe@example.com"];
console.log(incomplete.every((v) => v.trim() !== ""));
// false

true
false

🚀 Common Use Cases

• Form validation — confirm every required field is filled.
• Permission checks — verify all users in a list have a role.
• Data quality — ensure every record has required properties.
• Numeric bounds — all scores above a passing threshold.
• Type guards — every item is a string or number as expected.
• Feature flags — all services report healthy status.

📝 Notes

• Empty arrays return true by specification.
• Skipped holes in sparse arrays are still visited; holes behave like undefined.
• Return explicit booleans in callbacks for clarity, even though truthy/falsy works.
• Do not mutate the array inside the callback in ways that change indexes you have not visited yet.
• every() does not create a new array—use filter() when you need matches.
• Available since ES5; excellent baseline compatibility.

💡 Best Practices