Q: How to show single tooltip with data and labels from 3 (multiple) dataset?

Attempt to answer this question: https://stackoverflow.com/q/67339024/12511801

by MauricioSO2021

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js"></script>
<div style="width:75%;">
  <canvas id="canvas"></canvas>
</div>

JavaScript

window.chartColors = {
  red: 'rgb(255, 99, 132)',
  orange: 'rgb(255, 159, 64)',
  yellow: 'rgb(255, 205, 86)',
  green: 'rgb(75, 192, 192)',
  blue: 'rgb(54, 162, 235)',
  purple: 'rgb(153, 102, 255)',
  grey: 'rgb(231,233,237)'
};

// it's the result of "https://corona.lmao.ninja/v3/covid-19/historical/"+currentCountry+"?lastdays=all": 
var full_data = {
    "country": "USA",
    "province": ["mainland"],
    "timeline": {
        "cases": {
            "1/22/20": 1,
            "1/23/20": 1,
            "1/24/20": 2,
            "1/25/20": 2,
            "1/26/20": 5,
            "1/27/20": 5,
            "1/28/20": 5,
            "1/29/20": 6,
            "1/30/20": 6,
            "1/31/20": 8,
            "2/1/20": 8,
            "2/2/20": 8,
            "2/3/20": 11,
            "2/4/20": 11,
            "2/5/20": 11,
            "2/6/20": 12,
            "2/7/20": 12,
            "2/8/20": 12,
            "2/9/20": 12,
            "2/10/20": 12,
            "2/11/20": 13,
            "2/12/20": 13,
            "2/13/20": 14,
            "2/14/20": 14,
            "2/15/20": 14,
            "2/16/20": 14,
            "2/17/20": 14,
            "2/18/20": 14,
            "2/19/20": 14,
            "2/20/20": 14,
            "2/21/20": 16,
            "2/22/20": 16,
            "2/23/20": 16,
            "2/24/20": 16,
            "2/25/20": 16,
            "2/26/20": 16,
            "2/27/20": 17,
            "2/28/20": 17,
            "2/29/20": 25,
            "3/1/20": 32,
            "3/2/20": 55,
            "3/3/20": 74,
            "3/4/20": 107,
            "3/5/20": 184,
            "3/6/20": 237,
            "3/7/20": 403,
            "3/8/20": 519,
            "3/9/20": 594,
            "3/10/20": 782,
            "3/11/20": 1147,
            "3/12/20": 1586,
            "3/13/20": 2219,
            "3/14/20": 2978,
            "3/15/20": 3212,
            "3/16/20": 4679,
            "3/17/20": 6512,
            "3/18/20": 9169,
           ...