JSFiddle - React, Tailwind, and code Playground

HTML

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

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

JavaScript

var jsonData = [
  {billDate: {type: "date string"}, "userName": {type: "string"}},
  {billDate:"2020-02-05", "userName": 'user1&&userId1&&param1'},
  {billDate:"2019-10-15", "userName": 'user2&&userId2&&param2'},
  {billDate:"2015-12-22", "userName": 'user3&&userId3&&param3'},
  {billDate:"2019-11-09", "userName": 'user1&&userId4&&param1'}
  ];

var pivot = new Flexmonster({
	container: "pivot-container",
  customizeCell: customizeCellFunction,
  componentFolder: "https://cdn.flexmonster.com/",
		toolbar: true,
		report: {
    dataSource: {
    	data: jsonData,
      dataSourceType: "json"
    },
    slice: {
      reportFilters: [],
      rows: [{uniqueName:"billDate"}],
      columns: [
        {
          uniqueName: "[Measures]"
        }
      ],
      measures: [{uniqueName:"userName"}]
    },
    options: {
      grid: {
       type: 'flat'
      }
    }
  }
	});

function customizeCellFunction(cell, data) {
    let resolveLinkProperties = function(data) {
      let link = 'wwww.somelink.com/${0}?param=${1}';
      let parts = data.member.caption.split('&&');
      let caption = parts[0];
      if (parts.length > 1) {
        parts.shift();
      }
      for(let i = 0; i < parts.length; i++) {
        link = link.replace('${' + i + '}', parts[i]);
      }
      return {caption: caption, link: link};
    };

		if (data.hierarchy && data.hierarchy.uniqueName == "userName" && data.member) {
      let hl = resolveLinkProperties(data);
      cell.text = hl.caption;
    }
		
    
    // hl.link - is hyperlink with replaced parameters
}