JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://s3.amazonaws.com/flexmonster/2.3/demo.css">
<script src="https://cdn.flexmonster.com/flexmonster.js"></script>
<button onclick="expand()">
 expand year
</button>

<button onclick="onChange()">
 update grid
</button>
<div id="pivot-container"></div>

CSS

.editable {
  padding: 0 !important;
  z-index: 1 !important;
}

.editable input {
  width: 100%;
  height: 100%;
  background-color: transparent;
  border: 0px solid;
  padding-left: 4px !important;

}

JavaScript

new Flexmonster({
  container: "#pivot-container",
  componentFolder: "https://cdn.flexmonster.com/",
  width: "100%",
  height: 600,
  toolbar: true,
  report: getReport()
});

flexmonster.customizeCell(function(cell, data) {
  if (data && data.type == "value" && !isNaN(data.value) && data.level == 0 && !data.isTotal) {
    cell.addClass("editable");
    cell.text = `<input type="text" value="${data.label}" data-cell='${JSON.stringify(data)}'>`;
  }
})

function onChange(event) {
	
	flexmonster.updateData({ data: [{
    ScenarioKey: 1,
    ScenarioName: 'Actual',
    OrganizationKey: 3,
    OrganizationName: 'Northeast Division',
    AccountKey: 80,
    AccountDescription: 'Building Leasehold',
    Amount: 9000,
    Year: '2010',
    Month: '12'
  }] }, { partial: true });
}

function expand() {
	flexmonster.expandData('Year')
}

function getReport() {
	return {
    dataSource: {
        type: "json",
        data: [
        {
    ScenarioKey: 1,
    ScenarioName: 'Actual',
    OrganizationKey: 3,
    OrganizationName: 'Northeast Division',
    AccountKey: 80,
    AccountDescription: 'Building Leasehold',
    Amount: 586,
    Year: '2010',
    Month: '12'
  },
  {
    ScenarioKey: 2,
    ScenarioName: 'Budget',
    OrganizationKey: 3,
    OrganizationName: 'Northeast Division',
    AccountKey: 80,
    AccountDescription: 'Building Leasehold',
    Amount: 550,
    Year: '2010',
    Month: '12'
  },
  {
    ScenarioKey: 2,
    ScenarioName: 'Budget',
    OrganizationKey: 3,
    OrganizationName: 'Northeast Division',
    AccountKey: 81,
    AccountDescription: 'Vehicles',
    Amount: 380,
    Year: '2010',
    Month: '12'
  },
  {
    ScenarioKey: 1,
    ScenarioName: 'Actual',
    OrganizationKey: 3,
    OrganizationName: 'Northeast Division',
    AccountKey: 81,
    AccountDescription: 'Vehicles',
    Amount: 363,
    Year: '2010',
    Month: '12'
  },
  {
    ScenarioKey: 1,
    ScenarioName: 'Actual',
    OrganizationKey: 3,
    OrganizationName: 'Northeast...