Check if each item in an array is identical in JavaScript

function identical(array) {
    for(var i = 0; i < array.length - 1; i++) {
        if(array[i] !== array[i+1]) {
            return false;
        }
    }
    return true;
}

In ES5, you could do:

arr.every(function(v, i, a) {
   // first item: nothing to compare with (and, single element arrays should return true)
   // otherwise:  compare current value to previous value
   return i === 0 || v === a[i - 1];
});

.every does short-circuit as well.