Increment a KnockoutJS observable in an good expressive way

Question

Is there a compact way to increment a KnockoutJS observable in a high expressive way so the code gain in readability?

I would like to avoid this syntax:

var counter = ko.observable(0);

// increment the counter as we know today
counter(counter() + 1);

Instead I would like a more expressive syntax like:

counter.increment();

This kind of API should also accept an argument to define the value of the increment:

counter.increment(10);
counter.increment(-1);

I didn't found anything like this in the official documentation and other similar questions here report just the standard syntax which in my opinion is extremely difficult to read.

Answer 1

You could either extend the individual observable to support incrementing or apply it to all observables.

// for individual
ko.extenders['incrementable'] = function (target, enabled) {
    if (enabled) {
        target.increment = function (incValue) {
            this(this() + (incValue || 1));
        }.bind(target);
    }
    return target;
};
var counter = ko.observable(0).extend({ incrementable: true });
counter.increment();

// or for all
ko.observable.fn.increment = function (incValue) {
    this(this() + (incValue || 1));
};