未能读取'selectionStart'属性来自'HTMLInputElement':

我正在使用绑定句柄。如果我删除此代码，我的代码将被保存。但如果我使用这段代码会引发错误。

未捕获的InvalidStateError:未能从"HTMLInputElement"读取"selectionStart"属性：输入元素的类型（"复选框"）不支持选择

 ko.bindingHandlers.wysiwyg = {
        init: function (element, valueAccessor, allBindingsAccessor) {
            debugger;
            var options = allBindingsAccessor().wysiwygOptions || {};
            var value = ko.utils.unwrapObservable(valueAccessor());
                    //value = value.text();
            //var v = value[0].childNodes[0].data;
            var $e = $(element);
            $.extend(true, {
                initialContent: value
            }, options);
            $e.wysiwyg(options);
            //handle the field changing
            function detectFn() {
                var observable = valueAccessor();
                var newvalue = $e.wysiwyg("getContent");
                observable(newvalue);
            }
            var current = $e.wysiwyg('document');
            var timer;
            current.bind({
                keyup: function () {
                    clearTimeout(timer);
                    timer = setTimeout(detectFn, 1000);
                }
            });
            //handle disposal (if KO removes by the template binding)
            ko.utils.domNodeDisposal.addDisposeCallback(element, function () {
                $e.wysiwyg('destroy');
            });

        },
        update: function (element, valueAccessor) {
            var value = ko.utils.unwrapObservable(valueAccessor());
            $(element).wysiwyg("setContent", value);
            ko.bindingHandlers.value.update(element, valueAccessor);
        }
    };