There are multiple ways to check if an object is an array in JavaScript. Let us look at some of these −
Using Array.isArray()
All modern browsers support this method.
Example
console.log(Array.isArray(undefined))
console.log(Array.isArray(null))
console.log(Array.isArray(""))
console.log(Array.isArray({}))
console.log(Array.isArray([]))
console.log(Array.isArray([1, "hello"]))
console.log(Array.isArray(new Array()))Output
false false false false true true true
constructor check
You can use arr.constructor === Array to determine is an object is array. This doesnt work for all objects though.
Example
// This will fail: console.log(undefined.constructor === Array)
// This will fail: console.log(null.constructor === Array)
console.log("".constructor === Array)
console.log({}.constructor === Array)
console.log([].constructor === Array)
console.log([1, "hello"].constructor === Array)
console.log(new Array().constructor === Array)Output
false false true true true