Python-like iterators for using .next() in a sequence

iter.js

this.iter = function iter(array) {
    var copy = array.slice();
    var i    = 0;
    var max  = copy.length - 1;
    
    var next = function next() {
        var index = i
        i += 1
        
        if (index > max) {
            return undefined
        } else {
            return copy[index]
        }
    }
    
    return {
        next: next
    }
};