我知道有人提出了这方面的变化,但我的要求是,不需要格式化/舍入输入的值,我甚至不允许用户在小数点后输入多个数字.我有一些适用于decimalFormatter绑定处理程序的东西,但它很笨重 – 也就是说,它允许你输入像’20’这样的值.并且由于我编写正则表达式的方式,您无法擦除所有值.我意识到我可以修改它以接受整个条目的可选数字,但我真正想要的是,如果用户删除该值,它将恢复为0.0.并且,允许他们进入’20’.然后选项卡(onblur)并将其重新格式化为20.0,使其看起来更完整.目前,如果用户输入’20’.然后保存表单,它确实存储整数值20,当你重新打开/检索数据库中的值时,它显示20.0,所以它在重新加载时看起来很好.

我想过添加一个onblur事件,但是我们不想在覆盖被淘汰的数据绑定时做到这一点.我们希望保持ko视图模型的所有约束,因此这不是一个选项.我也看到一些建议计算的observable(例如这个SO post)但我的绑定已经做到了.在第二个想法,淘汰赛event binding将成为这里的方式???

HTML：

<input style="width:38px" data-bind="decimalFormatter: percentage"/>

JavaScript的：

ko.bindingHandlers.decimalFormatter = {
    init: function (element,valueAccessor) {
    var initialValue;

    //$(element).on('keydown',function (event) {
    $(element).keydown(function (event) {
        initialValue = $(element).val();

        // Allow: backspace,delete,tab,escape,and enter
        if (event.keyCode == 46 || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 27 || event.keyCode == 13 ||
        // Allow: Ctrl combinations
        (event.ctrlKey === true) ||
        // Allow decimal/period
        (event.keyCode === 110) || (event.keyCode === 190) ||
        // Allow: home,end,left,right
        (event.keyCode >= 35 && event.keyCode <= 39)) {
            // let it happen,don't do anything
            return;
        }
        else {
            // Ensure that it is a number and stop the keypress
            if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && (event.keyCode < 96 || event.keyCode > 105)) {
                event.preventDefault();
            }
        }
    });

    $(element).keyup(function (event) {
        if (!$(element).val().match(/^\d+\.?\d?$/)) {
            event.preventDefault();
            $(element).val(initialValue);
        }
        else
            return;
    });        

    var observable = valueAccessor();

    var interceptor = ko.computed({
        read: function () { return formatWithComma(observable(),1); },write: function (newValue) {
            observable(reverseFormat(newValue,1));
        }
    });

    if (element.tagName == 'INPUT')
        ko.applyBindingsToNode(element,{ value: interceptor });
    else
        ko.applyBindingsToNode(element,{ text: interceptor });
    },update: function (element,valueAccessor) {
    }
}

// Formatting Functions
function formatWithComma(x,precision,seperator) {
    var options = {
        precision: precision || 2,seperator: seperator || '.'
    }
    var formatted = parseFloat(x,10).toFixed(options.precision);
    var regex = new RegExp('^(\\d+)[^\\d](\\d{' + options.precision + '})$');
    formatted = formatted.replace(regex,'$1' + options.seperator + '$2');
    return formatted;
}

function reverseFormat(x,seperator: seperator || '.'
    }

    var regex = new RegExp('^(\\d+)[^\\d](\\d+)$');
    var formatted = x.replace(regex,'$1.$2');
    return parseFloat(formatted);
}

var viewmodel = function () {
    var self = this;
    self.percentage = ko.observable(20.0);
};

var vm = new viewmodel();
ko.applyBindings(vm);

JSFiddle

var vm = function(){   
this.Amount=ko.observable(""); 
this.OnloadAmount=ko.observable(143); //onLoad Test
ko.bindingHandlers.autoNumeric = {
       init: function (el,valueAccessor,bindingsAccessor,viewmodel) {
            var $el = $(el),bindings = bindingsAccessor(),settings = bindings.settings,value = valueAccessor();

            $el.autoNumeric(settings);
            $el.autoNumeric('set',parseFloat(ko.utils.unwrapObservable(value()),10));
            $el.change(function () {
                value(parseFloat($el.autoNumeric('get'),10));
            });
        },update: function (el,newValue = ko.utils.unwrapObservable(valueAccessor()),elementValue = $el.autoNumeric('get'),valueHasChanged = (newValue != elementValue);

            if ((newValue === 0) && (elementValue !== 0) && (elementValue !== "0")) {
                valueHasChanged = true;
            }

            if (valueHasChanged) {
                $el.autoNumeric('set',newValue);
            }
        }
    };
}

  ko.applyBindings(new vm());

<input type="text"  data-bind="autoNumeric:$data.Amount,settings:{mDec:1,aSep: ''} " />