我会小心地访问/修改以_开始的私有变量。您可能会发现自己有意外的行为。为什么不触发canvas mousemove事件呢

function openToolTip (myChart, index) {
    var mouseMoveEvent, meta, point, rectangle, value;
    meta = myChart.getDatasetMeta(0);
    rectangle = myChart.canvas.getBoundingClientRect();
    point = meta.data[index].getCenterPoint();
    mouseMoveEvent = new MouseEvent('mousemove', {
      clientX: rectangle.left + point.x,
      clientY: rectangle.top + point.y
    });
    myChart.canvas.dispatchEvent(mouseMoveEvent);
  },

要关闭工具提示，只需触发mouseout事件

function closeToolTip (myChart) {
    var mouseOutEvent = new MouseEvent('mouseout');
    return myChart.canvas.dispatchEvent(mouseOutEvent);
  }

下面的代码将处理一个或多个工具提示。

function openTip(oChart,datasetIndex,pointIndex){
   if(window.oChart.tooltip._active == undefined)
      window.oChart.tooltip._active = []
   var activeElements = window.oChart.tooltip._active;
   var requestedElem = window.oChart.getDatasetMeta(datasetIndex).data[pointIndex];
   for(var i = 0; i < activeElements.length; i++) {
       if(requestedElem._index == activeElements[i]._index)  
          return;
   }
   activeElements.push(requestedElem);
   //window.oChart.tooltip._view.body = window.oChart.getDatasetMeta(datasetIndex).data;
   window.oChart.tooltip._active = activeElements;
   window.oChart.tooltip.update(true);
   window.oChart.draw();
}
function closeTip(oChart,datasetIndex,pointIndex){
   var activeElements = window.oChart.tooltip._active;
   if(activeElements == undefined || activeElements.length == 0)
     return;
   var requestedElem = window.oChart.getDatasetMeta(datasetIndex).data[pointIndex];
   for(var i = 0; i < activeElements.length; i++) {
       if(requestedElem._index == activeElements[i]._index)  {
          activeElements.splice(i, 1);
          break;
       }
   }
   window.oChart.tooltip._active = activeElements;
   window.oChart.tooltip.update(true);
   window.oChart.draw();
}

@BeetleJuice提供的完整解决方案-https://jsfiddle.net/ucvvvnm4/5/

对于Chart.js@3，以下是官方解决方案：https://www.chartjs.org/docs/latest/samples/advanced/programmatic-events.html

function triggerTooltip(chart) {
  const tooltip = chart.tooltip;
  if (tooltip.getActiveElements().length > 0) {
    tooltip.setActiveElements([], {x: 0, y: 0});
  } else {
    const chartArea = chart.chartArea;
    tooltip.setActiveElements([
      {
        datasetIndex: 0,
        index: 2,
      }, {
        datasetIndex: 1,
        index: 2,
      }
    ],
    {
      x: (chartArea.left + chartArea.right) / 2,
      y: (chartArea.top + chartArea.bottom) / 2,
    });
  }
  chart.update();
}