function check() {
var ckl = document.getElementById("RadioButtonList1");
var ck = ckl.getElementsByTagName("input");
for (var i = 0; i < ck.length; i++) {
if (ck[i].checked) {
var text = ckl.cells[i].innerText;
var value = ck[i].value;
}
}
}
<div>
<asp:RadioButtonList ID="RadioButtonList1" runat="server">
<asp:ListItem Value="我是value1">我是text1</asp:ListItem>
<asp:ListItem Value="我是value2">我是text2</asp:ListItem>
<asp:ListItem Value="我是value3">我是text3</asp:ListItem>
</asp:RadioButtonList>
<asp:Button ID="Button2" runat="server" Text="js获取选中值" OnClientClick="check()" />
</div>