Array.prototype.every(callback) answers one question: do all elements pass this test? It returns a boolean, stops early on the first failure, and does not mutate the array.
array.every((element, index, array) => test)
all pass → true
one fails → false (stops early)
empty [] → true
pair with: some() (any pass?)
read-only · ES5Call array.every. Start with this line.
array.every(callback)| Call | What it does |
|---|---|
array.every(callback) | Primary signature. |
array.every(...) | Call with the arguments your case needs. |
Built into JavaScript. Call every(...) on an array instance — no import required.
array.every(callback)| Parameter | Description |
|---|---|
| Array | Required. Values to test |
| Callback | Required. Returns truthy/falsy per element |
| thisArg | Optional. Optional this for the callback |
| Return Value | Description |
|---|---|
| * | true or false |
Return true only when every element passes the modulo test.
const numbers = [2, 4, 6, 8, 10];
const allEven = numbers.every((num) => num % 2 === 0);
console.log(allEven);
// true[2, 4, 6, 8, 10].num % 2 === 0 is true for every item.true. The whole list satisfies the rule.false When One Element FailsAs soon as a value fails the rule, every() stops.
const numbers = [2, 4, 6, 8, 10];
const allGreaterThanTen = numbers.every((num) => num > 10);
console.log(allGreaterThanTen);
// false2 > 10 is false.false. One failure means “not every”.trueZero elements means zero failures — a common beginner surprise.
const empty = [];
const result = empty.every((n) => n > 0);
console.log(result);
// truetrue.arr.length when empty should mean “invalid”.Array.prototype.every() has been part of JavaScript since ES5 (2009). It is one of the most widely supported array methods.
Supported in Chrome 1+, Firefox 1.5+, Safari 3+, Edge 12+, IE 9+, and all modern Node.js versions.
Bottom line: Safe everywhere modern apps run, including IE9+. No polyfill needed for typical targets.
Learn how to fill all or part of an array with a static value.
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