memoNewValue.js

var memoizeNewValue = function() {
    var old = null;
    return function(newVal){
        if(newVal === old) {
            return false;
        } else {
            old = newVal;
            return true;
        }
    }
};

var isNewValue = memoizeNewValue(function(value) {});

if(isNewValue()) {
  // Do something.
}