首先是-1.7976931348623157E 308的来源.它等于AjaxControlToolkit.NumericUpDownBehavior的Minimum属性,它在Sys.Application.init Event处理程序之一中调用：

Sys.Application.add_init(function() {
    $create(AjaxControlToolkit.NumericUpDownBehavior,{"Maximum":1.7976931348623157E+308,"Minimum":-1.7976931348623157E+308,/* other non relevant stuff */);
});

所以,这里没有魔法,只有Double的最小值.最低是与10618版相比的新财产.

接下来,为什么一旦页面显示就显示？这是因为在AjaxControlToolkit.NumericUpDownBehavior.prototype中定义的readValue函数中的值this._min(等于$create中的Minimum参数)如果为空,则分配给输入. readValue来源：

readValue : function() {
        /// <summary>
        /// Parse value of textBox and this._currentValue to be that value.
        /// this._currentValue = this._min if some there is an exception
        /// when attempting to parse.
        /// Parse int or string element of RefValues
        /// </summary>

        if (this._elementTextBox) {
            var v = this._elementTextBox.value;
// The _currentValue of NumericUpDown is calculated here 
            // if textBox empty this._currentValue = this._min
            if(!this._refValuesValue) {
                if(!v) {
                    this._currentValue = this._min;
                } else {
                    try {
                        this._currentValue = parseFloat(v);
                    } catch(ex) {
                        this._currentValue = this._min;
                    }
                }
                if(isNaN(this._currentValue)) {
                    this._currentValue = this._min;
                }
// And assigned here. In case of empty input we will get -1.7976931348623157E+308 if Minimum was not changed
                this.setCurrentToTextBox(this._currentValue);
                this._valuePrecision = this._computePrecision(this._currentValue);
            } else {
                if(!v) {
                    this._currentValue = 0;
                } else {
                    var find = 0;
                    for (var i = 0; i < this._refValuesValue.length; i++) {
                        if (v.toLowerCase() == this._refValuesValue[i].toLowerCase()) {
                            find = i;
                        }
                    }
                    this._currentValue = find;
                }
                this.setCurrentToTextBox(this._refValuesValue[this._currentValue]);
            }
        }
    }

在最低版本之前,在版本10618中,默认值为0.所以我认为描述的问题可以通过在扩展器声明中明确指定最小值来解决：

<ajaxToolkit:NumericUpDownExtender ID="NumericExtenderFooNum" runat="server" 
     Minimum="0"
     TargetControlID="txtFooNum"
     TargetButtonDownID="FooBack" TargetButtonUpID

我发现另一件事是,新版本的IE中的更改事件调度失败(使其工作兼容性视图应该启用,但我认为这不是公共网站的选项).

问题在于setCurrentToTextBox函数.如果使用document.createEvent创建,事件对象在处理函数(例如,验证处理程序)中始终为空.要解决此问题,应将条件交换,因此IE中的所有事件将使用createEventObject创建.

// Current implementation of version 20229
setCurrentToTextBox : function(value) {
            // full sources are not shown,only if matters here

            if (document.createEvent) {
                // event is created using createEvent
            } else if( document.createEventObject ) {
                // event is created using createEventObject 
            }
        }
    }

// Updated implementation
setCurrentToTextBox : function(value) {
            // full sources are not shown,only if matters here

            if (document.createEventObject) {
                // event is created using createEventObject 
            } else if(document.createEvent) {
                // event is created using createEvent
            }
        }
    }