My97DatePicker点击清空按钮后，ng-model值不变

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<div class="form_text form_m fl">
<input class="startDate Wdate" id="startDate" name="startDate" ng-model="startDate" type="text" onfocus="WdatePicker({dateFmt:'yyyy-MM-dd',maxDate:'#F{$dp.$D(\'endDate\')}',onpicked: function(){$(this).trigger('change')},skin:'whyGreen',maxDate:'%y-%M-%d',onclearing: function(){if(!confirm('日期框的值为:'+this.value+', 确实要清空吗?'))return false;} })" readonly="false"/>
</div>