js报错 TypeError: cannot use 'in' operator to search for 'length' in '[{"id":1,"pid":0...'

layui.use(['treetable','form'],function(){
    var data = document.querySelector("#sysMenus").value;
    //data=[{"id":1,"pid":0,"code":"home","name":"主页","targetLink":"/","icon":"","level":0,"pCode":"","sort":1,"createTime":"2018-12-25 23:52:17","updateTime":""}]

    var treetable = layui.treetable
        ,form = layui.form
        ,layer = layui.layer;
    treetable.render({
        elem: '#tableId',
        data: data,
        field: 'id',
        cols: [
            {field: "id", title: "ID"}
        ]
    });
});

异常信息：

TypeError: cannot use 'in' operator to search for 'length' in '[{"id":1,"pid":0...'

解决方法：

var data = document.querySelector("#sysMenus").value;
//data=[{"id":1,"pid":0,"code":"home","name":"主页","targetLink":"/","icon":"","level":0,"pCode":"","sort":1,"createTime":"2018-12-25 23:52:17","updateTime":""}]
 

转成 json 就行了