How to Check if an Array Is Empty in JavaScript

Check if an Array Is Empty in JavaScript

In JavaScript, arrays are a common data structure used to store lists of values such as ["apple", "banana", "cherry"]. But sometimes, you may want to know: is the array empty? That is, does it have any items at all?

There are several simple and reliable ways to check for an empty array, each useful in different scenarios. Whether you’re validating user input, cleaning up your logic flow, or debugging a data pipeline, understanding how to detect empty arrays is a basic yet crucial skill.

Method 1: Check Array Length

The most direct way is to use the length property of the array. If the length is 0, the array is empty. This method is simple, readable, and efficient.

const fruits = ["apple", "banana"];
const emptyList = [];

if (fruits.length === 0) {
  console.log("fruits is empty");
} else {
  console.log("fruits is not empty");
}

if (emptyList.length === 0) {
  console.log("emptyList is empty");
} else {
  console.log("emptyList is not empty");
}

fruits is not empty
emptyList is empty

Method 2: Convert to Boolean Using `!array.length`

If you're comfortable with shorthand logic, you can check the array’s length in a more concise way using the logical NOT operator !. This evaluates to true if the array has zero items.

const items = [];

if (!items.length) {
  console.log("items is empty");
}

items is empty

Method 3: Defensive Check with Optional Chaining

When working with data you didn’t create—such as API responses—you might encounter null or undefined instead of arrays. To guard against runtime errors, you can use optional chaining before accessing length.

let maybeArray = undefined;

if (!maybeArray?.length) {
  console.log("maybeArray is empty or not defined");
}

maybeArray is empty or not defined

Method 4: Using JSON String Check (Not Recommended)

Sometimes beginners use JSON.stringify() and compare the result to "[]". While this works technically, it’s not recommended because it’s slow, unreadable, and not idiomatic JavaScript.

 to check if it's empty.",
    "Although functional, this approach is inefficient and discouraged."
  ]'>const list = [];

if (JSON.stringify(list) === "[]") {
  console.log("list is empty");
}

list is empty

Common Use Cases

Checking if an array is empty is helpful in many real-world JavaScript tasks, such as:

Deciding whether to render a UI list or show a “No items” message
Validating user inputs (like selecting at least one option)
Skipping unnecessary processing on empty datasets

Edge Case to Watch Out For

Make sure you're actually dealing with an array. For example, an object or a string might not behave as expected. Use Array.isArray(variable) before checking length if the type is uncertain.

Final Thoughts

In the world of JavaScript, simplicity often wins. Checking array.length === 0 is the gold standard—clear, fast, and readable. But for advanced scenarios where the variable might be undefined or null, optional chaining gives you safe fallback behavior.

Now that you understand different ways to check if an array is empty, you’re better equipped to write clean and bug-free JavaScript code that responds gracefully to all kinds of data inputs.

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