Check if variable is Array

check_array.js

/**
 * Check whether an object is Array or not
 * @type Boolean
 * @param {object} subject is the variable that is
 * tested for Array identity check
 */
var isArray = (function () {
    // Use compiler's own isArray when available
    if (Array.isArray) {
        return Array.isArray;
    } 
 
    // Retain references to variables for performance
    // optimization
    var objectToStringFn = Object.prototype.toString,
        arrayToStringResult = objectToStringFn.call([]); 
 
    return function (subject) {
        return objectToStringFn.call(subject) === arrayToStringResult;
    };
}());


console.log( isArray(123) ); // false
console.log( isArray(true) ); // false
console.log( isArray("my little string") ); // false

var obj = {
	items: [
  	{id:1, name:'alpha'},
    {id:2, name:'beta'},
    {id:3, name:'gamma'},
  ]
};
console.log( isArray(obj) ); // false

var arr = ["Saab", "Volvo", "BMW"];
console.log( isArray(arr) ); // true