Set a path to options/tooltips/callbacks/afterTitle and pass parameter to Array

I'm working on a chart, I'm live updating the Chart every 5 seconds that the data comes in. I could manage to get the info from the database and update it really easy, but I just came across a problem with involves setting a path to a part of the chart, in the case: options->tootltips->callbacks->afterTitle and inside of it create an array and pass the array from the JSON to an array inside the callback.

Inside this patch, I made an example that didn't work, with is the //:

$.getJSON('loadchart.php', function(response) {
          myLineChart.data.datasets[0].data = response[0];
          myLineChart.data.datasets[1].data = response[1];
          myLineChart.data.datasets[2].data = response[2];
          myLineChart.data.datasets[3].data = response[3];
          myLineChart.data.labels = response[4];

          //The response array that I need is response[5];
          //myLineChart.options.tooltips.callbacks[1] = return response[tooltipItem[0]['index']]; 
          myLineChart.update();
        });

All my Chart so you can see the path:

var myLineChart = new Chart(ctx1, {
        type: 'line', 
        data: {
          labels: lbl,
          datasets: [
            {
              label: "Corrente 1",
              data: [],
              borderWidht: 6,
              borderColor: 'red',
              backgroundColor: 'transparent'
            },
            {
              label: "Corrente 2",
              data: [],
              borderWidht: 6,
              borderColor: 'blue',
              backgroundColor: 'transparent'
            },
            {
              label: "Corrente 3",
              data: [],
              borderWidht: 6,
              borderColor: 'green',
              backgroundColor: 'transparent'
            },
            {
              label: "Corrente Total",
              data: [],
              borderWidht: 6,
              borderColor: 'black',
              backgroundColor: 'transparent'
            },
          ]            
        },
        options: {
          animation:{
            update: 0
          },
          scales: {
            yAxes: [{
              ticks: {
                beginAtZero: true
              }
            }],
            xAxes: [{
              gridLines: {
                display: false
              }
            }]
          },

          title: {
            display: true,
            fontSize: 20,
            text: "Gráfico das Correntes"
          },

          labels: {
            fontStyle: "bold",
          },

          layout: {
            padding: {
              left: 0,
              right: 0,
              top: 0,
              bottom: 0
            }
          },
          tooltips: {
            enabled: true,
            mode: 'single',
            responsive: true,
            backgroundColor: 'black',
            titleFontFamily: "'Arial'",
            titleFontSize: 14,
            titleFontStyle: 'bold',
            titleAlign: 'center',
            titleSpacing: 4,
            titleMarginBottom: 10,
            bodyFontFamily: "'Mukta'",
            bodyFontSize: 14,
            borderWidth: 2,
            borderColor: 'grey',
            callbacks:{
              title: function(tooltipItem, data) {
                  return data.labels[tooltipItem[0].index];
              },
              afterTitle: function(tooltipItem, data) {
                var tempo = [];
                return tempo[tooltipItem[0]['index']]; 
              },
              label: function(tooltipItem, data) {
                    var label = data.datasets[tooltipItem.datasetIndex].label || '';                  
                    if (label) {
                        label += ': ';
                    }
                    label += (tooltipItem.yLabel)+"A";                  
                    return label;
              }
            }
          },

The part I need is this one:

afterTitle: function(tooltipItem, data) {
                var tempo = [];
                return tempo[tooltipItem[0]['index']]; 

from Set a path to options/tooltips/callbacks/afterTitle and pass parameter to Array