Checking for arrays

isArray

// from https://medium.com/devschacht/javascripts-new-private-class-fields-c60daffe361b

// METHOD 1: constructor property
// Not reliable
function isArray(value) {
  return typeof value == 'object' && value.constructor === Array;
}

// METHOD 2: instanceof
// Not reliable since an object's prototype can be changed
// Unexpected results within frames
function isArray(value) {
  return value instanceof Array;
}

// METHOD 3: Object.prototype.toString()
// Better option and very similar to ES6 Array.isArray()
function isArray(value) {
  return Object.prototype.toString.call(value) === '[object Array]';
}

// METHOD 4: ES6 Array.isArray()
function isArray(value) {
  return Array.isArray(value);
}