Array.isArray([1, 2, 3]); // true Array.isArray('asdf'); // false
var fruits = ["Banana", "Orange", "Apple", "Mango"]; var n = fruits.includes("Mango");
function isArray(value) { return Object.prototype.toString.call(value) === "[object Array]"; }
var extensions = ["image/jpeg","image/png","image/gif"]; if(extensions.indexOf("myfiletype") === -1){ alert("Image must be .png, .jpg or .gif"); }
var array = [1, 3], prizes = [[1, 3], [1, 4]], includes = prizes.some(a => array.every((v, i) => v === a[i])); console.log(includes);