Extenders in Knockout JS with multiple parameters

Question

Can one use extenders with multiple parameters in knockout.js

Example:

ko.extenders.currency = function(target, currencySymbol, position) {
    var result = ko.computed({
        read: target,  
        write: function(newValue) {
            var current = target(),
            if (position == 'left') {
                target(currencySymbol+target);
            } else {
                target(target+currencySymbol);
            }
        }
    }).extend({ notify: 'always' });

but then how would I bind it to observable?

this.One = ko.observable(one).extend({ currency: ???, currencySymbol: '£', position : 'left'});

Answer 1

You would need to use an object for that, for example:

ko.extenders.currency = function(target, options) {
    var currencySymbol = options.symbol,
        position = options.position;
    var result = ko.computed({
        read: target,  
        write: function(newValue) {
            var current = target(),
            if (position == 'left') {
                target(currencySymbol+target);
            } else {
                target(target+currencySymbol);
            }
        }
    }).extend({ notify: 'always' });

And then, you'll call it like this:

this.One = ko.observable(one).extend({ currency: { symbol: '£', position : 'left' } });

Or if you prefer a more readable code:

var currencyOptions = { symbol: '£', position: 'left' };
this.One = ko.observable(one).extend({ currency: currencyOptions });