let arrA = [1,1,1,5]
let arrB = [1,1,1,1]

isAllEqual(array) {
            if (array.length > 0) {
                return !array.some(function (value, index) {
                    return value !== array[0];
                });
            } else {
                return true;
            }
        },

isAllEqual(arrA)     //false
isAllEqual(arrB)     //true