easyui-textbox 只讀設置取消

<script>
$(function () {
$("#txt_beginAmount").attr('readonly', true);
$("#txt_beginAmount").attr('readonly', false);
})
</script>
<input type="text" class="txt02 easyui-textbox" name="txt_beginAmount" id="txt_beginAmount" data-options="required:true,width:160" />