JS: Array.isArray

Array.isArray ( value )

Return true if value is a array object. (not a array-like object.) Else, false.

// real array
console.log ( Array.isArray ( ["a", "b"] ) );
// true

// array-like object
console.log ( Array.isArray ( {0:"a", 1:"b" , length:2} ) );
// false

[see JS: Array-Like Object]

Reference

ECMAScript® 2016 Language Specification#sec-array.isarray