Sometimes a single match isn't enough. You want to know whether every item in an array passes a test: are all the fields filled in, are all the numbers positive, did every task get finished? That's what every() is for. It returns true only if all items pass, and false as soon as one fails. This guide covers how it works and where it fits.
 

Table of Contents

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What every() Does

Returns true or false: a plain boolean, not an item and not an index.

All items must pass: one failure is enough to make the result false.

Stops at the first failure: once an item fails, the rest never get checked.

Leaves the original array alone: it only reads through it.

let numbers = [2, 4, 6, 8];
let allEven = numbers.every(n => n % 2 === 0);

console.log(allEven); // true

 

Syntax and Parameters

array.every(function (item, index, array) {
  return condition;
});

item: the current element being checked.

index: its position in the array.

array: the full array. You'll rarely need it.

The function must return true or false: that decides whether the item passes.

 

Practical Examples

Checking that every score is a pass:

let scores = [72, 85, 90, 65];
console.log(scores.every(score => score >= 50)); // true

Checking that all form fields are filled:

let fields = ["Vi", "vi@email.com", "Bangalore"];
console.log(fields.every(field => field !== "")); // true

Checking that every task is done:

let tasks = [
  { title: "Study", done: true },
  { title: "Gym", done: false }
];

console.log(tasks.every(task => task.done)); // false

 

Things to Remember

It stops early: the moment one item fails, it returns false without checking the rest.

let numbers = [2, 4, 5, 8, 10];

numbers.every(n => {
  console.log(`Checking ${n}`);
  return n % 2 === 0;
});
// Checking 2
// Checking 4
// Checking 5

An empty array always gives true: with nothing to fail the test, it passes by default. This surprises a lot of people.

console.log([].every(n => n > 100)); // true

Guard against empty arrays when it matters: if "no items" should count as a failure, check the length too.

let items = [];
let allValid = items.length > 0 && items.every(i => i.valid);

 

Common Mistakes

Forgetting the empty array case: [].every(...) is true, which can hide bugs in validation code.

Forgetting to return a value: with curly braces, you need an explicit return, otherwise nothing passes and the result is false.

Using it to find the failing item: every() only says yes or no. Use find() with the opposite condition to get the item that failed.
 

Conclusion

Frequently Asked Questions (FAQs)

Always true, because there's no item that could fail the test.

2.What's the difference between every() and some()?

every() needs all items to pass. some() needs only one.

3.Does every() change the original array?

No. It only reads through the array.