JavaScript Array.isArray() Static Method

Array.isArray()

The Array.isArray() method in JavaScript is used to determine if a given value is an array. It returns a boolean indicating whether the provided value is an array.

Syntax

Array.isArray(value)

Parameters

Parameter	Description
value	The value to be checked if it is an array.

Return Value

The Array.isArray() method returns true if the provided value is an array; otherwise, it returns false.

---

Examples

1. Checking Arrays

In this example, the method is used to verify if various values are arrays.

console.log(Array.isArray([1, 2, 3])); // true
console.log(Array.isArray(["a", "b", "c"])); // true
console.log(Array.isArray(new Array(5))); // true

Output

true
true
true

2. Checking Non-Array Values

Non-array values such as objects, strings, and numbers return false.

console.log(Array.isArray({ key: "value" })); // false
console.log(Array.isArray("Hello World")); // false
console.log(Array.isArray(42)); // false

Output

false
false
false

3. Checking null and undefined

Both null and undefined are not arrays, so the method returns false.

console.log(Array.isArray(null)); // false
console.log(Array.isArray(undefined)); // false

Output

false
false

4. Using Array.isArray() in a Function

This example demonstrates a utility function to process arrays differently from other types.

function processInput(input) {
    if (Array.isArray(input)) {
        console.log("Input is an array:", input);
    } else {
        console.log("Input is not an array:", input);
    }
}

processInput([10, 20, 30]); // Input is an array
processInput("Hello"); // Input is not an array

Output

Input is an array: [10, 20, 30]
Input is not an array: Hello

The function utilizes Array.isArray() to distinguish between arrays and other types.