JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdn.flexmonster.com/flexmonster.js"></script>

<div id="pivot-container"></div>

JavaScript

let pivot = new Flexmonster({
  container: "pivot-container",
  componentFolder: "https://cdn.flexmonster.com/",
  toolbar: true,
  report: {
    dataSource: {
      data: getData(),
      mapping: {
        "Date1": {
          type: "datetime",
          caption: "Date1",
        },
        "Date2": {
          type: "datetime",
          caption: "Date2"
        },
        "Date3": {
          type: "datetime",
          caption: "Date3"
        },
         "Date4": {
          type: "datetime",
          caption: "Date4"
        },
      }
    },
    slice: {
      rows: [{
          uniqueName: "Date1"
        },
        {
          uniqueName: "Date2",
        },
        {
          uniqueName: "Date3",
        }, 
        {
          uniqueName: "Date4",
        }
      ],
      columns: [{
        uniqueName: "[Measures]"
      }],
      measures: []
    },
    options: {
      grid: {
        type: "flat",
        showTotals: "off",
        showGrandTotals: "off"
      },
      dateTimePattern: "yyyy-MM-dd"
    }
  }
});

function getData() {
  return [{
    "Date1": 1667551668000,
    "Date2":  -62135596800000,
    "Date3": "2012-05-23T10:34:54.123Z",
    "Date4": "0001-01-01T00:00:00.000Z",
  }, ]
}