How to know what graph are you referring with multiple eCharts graphs in one page with `renderItem` callback

If there are more then one charts in a single page and you got some functions like this to change the graph type

function setGraph_chartName1_to_customType(e){ //there are multiple functions like this
    chartName1.setOption({
        series: [{
            customtypename: 'customType',
            renderItem: renderItemCallback,
        }]
    });
       // ... somethings
}

and then in renderItemCallback() you have to identify the chart needed because the function renderItemCallback() it’s used for more then one chart (eg. chartName1, chartName2, chartName3)

function renderItemCallback(params, api) {
    var points_array = chartName1.getOption().dataset[0].source; //HERE IS NEEDED THE CHART OBJECT
    if (points_array.length) {
             // ... somethings
    }
}

Now, after the code, see the question(s):

How to get chartName1 as referer graph inside renderItemCallback function?

Is there a way to send other parameters to the callback function in addition to params, api (to identify the graph you are working on)?