解决方法:
<input id=butDelete runat=server type=button value=删除 onclick="javascript:if(confirm('请确认是否删除此记录!')==false) return false;"/>
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protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Button1.Attributes.Add("onclick","return confirm('是否删除?')");
}
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Button1.Attributes.Add("onclick","return confirm('确认?')");
button.attributes.add("onclick","if(confirm('are you sure...?')){return true;}else{return false;}")