KnockoutJS accounting.js binding handler

ko.bindingHandlers.currency.js

(function (root, factory) {
    if (typeof define === 'function' && define.amd) {
        // AMD. Register as an anonymous module.
        define(["jquery", "knockout", "accounting"], factory);
    } else {
        // Browser globals
        factory($, ko, accounting);
    }
}(this, function ($, ko, accounting) {
    ko.bindingHandlers.currency = {
        currencyOptions: ko.observable({ symbol: "$", decimal: ".", thousand: ",", precision: 2, format: "%s%v" }), //Set the default values.
        init: function (element, valueAccessor, allBindingsAccessor) {
            //only inputs need this, text values don't write back
            if ($(element).is("input") === true) {
                var underlyingObservable = valueAccessor(),
                    interceptor = ko.computed({
                        read: underlyingObservable,
                        write: function (value) {
                            if (value === "") {
                                underlyingObservable(null);
                            } else {
                                underlyingObservable(accounting.unformat(value));
                            }
                        }
                    });

                ko.bindingHandlers.value.init(element, function () {
                    return interceptor;
                }, allBindingsAccessor);
            }
        },
        update: function (element, valueAccessor, allBindingsAccessor) {
            // Available fields in options object, matching 'settings.currency'
            var currencyOptions = ko.unwrap(allBindingsAccessor().currencyOptions !== undefined ? allBindingsAccessor().currencyOptions : ko.bindingHandlers.currency.currencyOptions);
            var value = ko.unwrap(valueAccessor());

            var formatCurrency = function (float, options) {
                return accounting.formatMoney(float, options);
            };

            if ($(element).is("input") === true) {
                //leave the boxes empty by default
                value = value !== null && value !== undefined && value !== "" ? formatCurrency(parseFloat(value), currencyOptions) : "";
                $(element).val(value);
            } else {
                //text based bindings its nice to see a 0 in place of nothing
                value = value || 0;
                $(element).text(formatCurrency(parseFloat(value), currencyOptions));
            }
        }
    };
}));

Usage:

<td data-bind="currency: amount, currencyOptions : { symbol: "$", format: '%s %v' }"></td>