asp.net button set textbox text

參考來源: ASP.NET on button click in user control set the value of a textbox in the main page using javascript
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找好久,原來是要送出 submit

<script type="text/javascript">
    function SetPage(a) {
        var txtFld = document.getElementById("<%=PageBox.ClientID%>");
        txtFld.value = a;
        document.forms[0].submit(); // or document.forms['formname'].submit()
        return false;
    }
</script>