Check if each item in an array is identical in JavaScript

Question

I need to test whether each item in an array is identical to each other. For example:

var list = ["l","r","b"]

Should evaluate as false, because each item is not identical. On the other hand this:

var list = ["b", "b", "b"]

Should evaluate as true because they are all identical. What would be the most efficient (in speed/resources) way of achieving this?

Answer 1

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

Answer 2

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.