easyui的combobox带checkbox的全选功能

var getData = function () {
    var data;
    $.ajax({
        url: '/getMATTypeList',
        type: 'get',
        async: false,
        success: function (result) {
            data = result;
            //数组头部添加元素
            data.unshift({"G_MATTYPENAME": "全选", "G_MATTYPECODE": ""});
        }
    });
    return data;
}

function  initMatTypeCombobox(){
    $('#G_MATTYPECODE').combobox({
        valueField: 'G_MATTYPECODE',
        textField: 'G_MATTYPENAME',
        multiple: true,
        editable: false,
        panelHeight: 200,
        readonly: false,
        data: getData(),
        onClick: function (record) {
            var valueField = $("#G_MATTYPECODE").combobox("options").valueField;
            if (!record[valueField]) {
                var data = $("#G_MATTYPECODE").combobox("getData");
                var values = $("#G_MATTYPECODE").combobox("getValues");
                var selectVaues = [];
                if ((data.length - 1) != values.length) {
                    data.reduce(function (prev, current, index, array) {
                        selectVaues.push(current[valueField]);
                    }, selectVaues);
                } else {
                    selectVaues.push(record[valueField]);
                }
                $("#G_MATTYPECODE").combobox('setValues', selectVaues);
            }
        },
        formatter: function (row) { //formatter方法就是实现了在每个下拉选项前面增加checkbox框的方法
            var opts = $("#G_MATTYPECODE").combobox('options');
            return '<input type="checkbox" class="combobox-checkbox">' + row[opts.textField]
        },
        onSelect: function (row) { //选中一个选项时调用
            var opts = $(this).combobox('options');
            //设置选中值所对应的复选框为选中状态
            var el = opts.finder.getEl(this, row[opts.valueField]);
            el.find('input.combobox-checkbox')._propAttr('checked', true);
        },
        onUnselect: function (row) {//不选中一个选项时调用
            var opts = $(this).combobox('options');
            var el = opts.finder.getEl(this, row[opts.valueField]);
            el.find('input.combobox-checkbox')._propAttr('checked', false);
        }
    });
}