echarts画图需要每隔5秒定时刷新，怎样消除之前画的图？

html:
<div class="chartContent">

<div id="multiple"></div>
</div>

JS:
var echart={

arrPrice:[],
arrRate:[],
time:[]
};

//***我用了一个getData（）来通过ajax实现获取实时数据；***
function getData(){
    $.ajax({
        url:‘mod.json‘,
        type:‘post‘,
        async:true,
        data:‘‘,
        dataType:‘json‘,
        success:function(data){
            for(i in data.result){
                echart.arrPrice.push(data.result[i].price);
                echart.arrRate.push(data.result[i].rise);
                echart.time.push(data.result[i].time);
            }
            drawChart();
        },
        error:function(){
            console.log(‘error‘)
        }
    });
}
**//drawChart()y用来实现echarts画图;**
    function drawChart(){
    var dom = document.getElementById("multiple");
    var myChart = echarts.init(dom);
    option = {
             xxx
            }
        ]
    };
    if (option && typeof option === "object") {
        myChart.setOption(option, true);
    }
}

window.setInterval(function(){

    //getData()
},3000);
来实现5秒定时刷新