import React, { forwardRef, useImperativeHandle, useState } from 'react';

export default forwardRef((props, ref) => {
  const text = Array(100).fill('should be scroll').join(' ')

  useImperativeHandle(ref, () => {
    return {
      getReactContainerClasses() {
        return ['custom-tooltip'];
      },
    };
  });

  return (
      <div
        className="custom-tooltip"
        style={{
          backgroundColor:'white',
          padding: '10px',
          width: '200px',
          maxHeight: '300px',
          overflowY: 'scroll',
          wordBreak: 'break-all',
        }}
      >
          {text}
      </div>
  );
});
'use strict';

import React, { useState, useRef } from 'react';
import { render } from 'react-dom';
import { AgGridReact, AgGridColumn } from 'ag-grid-react';
import 'ag-grid-community/dist/styles/ag-grid.css';
import 'ag-grid-community/dist/styles/ag-theme-alpine.css';
import CustomTooltip from './customTooltip.jsx';

const GridExample = () => {
  const [gridApi, setGridApi] = useState(null);
  const [gridColumnApi, setGridColumnApi] = useState(null);
  const [rowData, setRowData] = useState([]);
  const ref = useRef()
  const onGridReady = (params) => {
    setGridApi(params.api);
    setGridColumnApi(params.columnApi);
    // setRowData([{ athlete: 'hover here', age: 1 }]);
    const updateData = (data) => {
      setRowData(data);
    };

    fetch('https://www.ag-grid.com/example-assets/olympic-winners.json')
      .then((resp) => resp.json())
      .then((data) => updateData(data));
  };

  return (
    <>
    <div style={{ width: '100%', height: '100px' }} ref={ref}>
      <div
        style={{
          height: '100%',
          width: '100%',
        }}
        className="ag-theme-alpine"
      >
        <AgGridReact
          defaultColDef={{
            editable: true,
            sortable: true,
            minWidth: 100,
            filter: true,
            resizable: true,
            tooltipComponent: 'customTooltip',
          }}
          popupParent={ref.current}
          tooltipShowDelay={0}
          rowData={rowData.slice(0,3)}
          pinnedBottomRowData={rowData}
          frameworkComponents={{ customTooltip: CustomTooltip }}
          onGridReady={onGridReady}
        >
          <AgGridColumn
            field="athlete"
            minWidth={150}
            tooltipField="athlete"
            tooltipComponentParams={{ color: '#ececec' }}
          />
          <AgGridColumn field="age" />
        </AgGridReact>
      </div>
    </div>
     <div style={{ width: '100%', height: '100px' }} ref={ref}>
      <div
        style={{
          height: '100%',
          width: '100%',
        }}
        className="ag-theme-alpine"
      >
        <AgGridReact
          defaultColDef={{
            editable: true,
            sortable: true,
            minWidth: 100,
            filter: true,
            resizable: true,
            tooltipComponent: 'customTooltip',
          }}
          popupParent={ref.current}
          tooltipShowDelay={0}
          rowData={rowData.slice(0,3)}
          pinnedBottomRowData={rowData}
          frameworkComponents={{ customTooltip: CustomTooltip }}
          onGridReady={onGridReady}
        >
          <AgGridColumn
            field="athlete"
            minWidth={150}
            tooltipField="athlete"
            tooltipComponentParams={{ color: '#ececec' }}
          />
          <AgGridColumn field="age" />
        </AgGridReact>
      </div>
    </div>
    </>
  );
  
};

render(<GridExample></GridExample>, document.querySelector('#root'));
.custom-tooltip {
  position: absolute;
  width: 150px;
  height: 70px;
  border: 1px solid cornflowerblue;
  overflow: hidden;
  pointer-events: none;
  transition: opacity 1s;
}

.custom-tooltip.ag-tooltip-hiding {
  opacity: 0;
}

.custom-tooltip p {
  margin: 5px;
  white-space: nowrap;
}

.custom-tooltip p:first-of-type {
  font-weight: bold;
}
(function(global) {
    // simplified version of Object.assign for es3
    function assign() {
        var result = {};
        for (var i = 0, len = arguments.length; i < len; i++) {
            var arg = arguments[i];
            for (var prop in arg) {
                result[prop] = arg[prop];
            }
        }
        return result;
    }

    System.config({
        transpiler: 'plugin-babel',
        defaultExtension: 'js',
        paths:
            assign(
                {
                    // paths serve as alias
                    "npm:": "https://unpkg.com/",
                }, systemJsPaths),
        map: assign(
            {
                // css plugin
                'css': 'npm:systemjs-plugin-css/css.js',

                // babel transpiler
                'plugin-babel': 'npm:systemjs-plugin-babel@0.0.25/plugin-babel.js',
                'systemjs-babel-build': 'npm:systemjs-plugin-babel@0.0.25/systemjs-babel-browser.js',

                // react
                react: 'npm:react@16.13.1',
                'react-dom': 'npm:react-dom@16.13.1',
                'react-dom-factories': 'npm:react-dom-factories',
                redux: 'npm:redux@3.6.0',
                'react-redux': 'npm:react-redux@5.0.6',
                'prop-types': 'npm:prop-types',

                app: appLocation + 'app'
            },
            systemJsMap
        ), // systemJsMap comes from index.html

        packages: {
            react: {
                main: './umd/react.production.min.js'
            },
            'react-dom': {
                main: './umd/react-dom.production.min.js'
            },
            'react-dom/server': {
                main: '../umd/react-dom-server.browser.production.min.js'
            },
            'prop-types': {
                main: './prop-types.min.js',
                defaultExtension: 'js'
            },
            redux: {
                main: './dist/redux.min.js',
                defaultExtension: 'js'
            },
            'react-redux': {
                main: './dist/react-redux.min.js',
                defaultExtension: 'js'
            },
            app: {
                defaultExtension: 'jsx'
            },
            'ag-grid-react': {
                main: './main.js',
                defaultExtension: 'js'
            },
            'ag-grid-community': {
                main: './dist/ag-grid-community.cjs.js',
                defaultExtension: 'js'
            },
            'ag-grid-enterprise': {
                main: './dist/ag-grid-enterprise.cjs.js',
                defaultExtension: 'js'
            },
            '@ag-grid-community/react': {
                main: './main.js',
                defaultExtension: 'js'
            }
        },
        meta: {
            '*.jsx': {
                babelOptions: {
                    react: true
                }
            },
            '*.css': { loader: 'css' }
        }
    });
})(this);
<!DOCTYPE html>
<html lang="en">
	<head>
		<title>React example</title>
		<meta charSet="UTF-8"/>
		<meta name="viewport" content="width=device-width, initial-scale=1"/>
		<style media="only screen">
            html, body, #root {
                height: 100%;
                width: 100%;
                margin: 0;
                box-sizing: border-box;
                -webkit-overflow-scrolling: touch;
            }

            html {
                position: absolute;
                top: 0;
                left: 0;
                padding: 0;
                overflow: auto;
            }

            body {
                padding: 1rem;
                overflow: auto;
            }
        </style>
		<link rel="stylesheet" href="styles.css"/>
	</head>
	<body>
		<div id="root">Loading React example…</div>
		<script>
            var appLocation = './';
            var boilerplatePath = '';
            var systemJsMap = {
                "@ag-grid-community/all-modules/dist/styles/ag-grid.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-grid.css",
                "@ag-grid-community/core/dist/styles/ag-grid.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-grid.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-alpine-dark.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-alpine-dark.css",
                "@ag-grid-community/core/dist/styles/ag-theme-alpine-dark.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-alpine-dark.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-alpine.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-alpine.css",
                "@ag-grid-community/core/dist/styles/ag-theme-alpine.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-alpine.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-balham-dark.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-balham-dark.css",
                "@ag-grid-community/core/dist/styles/ag-theme-balham-dark.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-balham-dark.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-balham.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-balham.css",
                "@ag-grid-community/core/dist/styles/ag-theme-balham.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-balham.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-blue.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-blue.css",
                "@ag-grid-community/core/dist/styles/ag-theme-blue.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-blue.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-bootstrap.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-bootstrap.css",
                "@ag-grid-community/core/dist/styles/ag-theme-bootstrap.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-bootstrap.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-dark.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-dark.css",
                "@ag-grid-community/core/dist/styles/ag-theme-dark.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-dark.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-fresh.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-fresh.css",
                "@ag-grid-community/core/dist/styles/ag-theme-fresh.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-fresh.css",
                "@ag-grid-community/all-modules/dist/styles/ag-theme-material.css": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/styles/ag-theme-material.css",
                "@ag-grid-community/core/dist/styles/ag-theme-material.css": "https://unpkg.com/@ag-grid-community/core@25.3.0/dist/styles/ag-theme-material.css",
                "@ag-grid-community/react": "https://unpkg.com/@ag-grid-community/react@25.3.0/",
                "@ag-grid-community/angular": "https://unpkg.com/@ag-grid-community/angular@25.3.0/",
                "@ag-grid-community/vue": "https://unpkg.com/@ag-grid-community/vue@25.3.0/",
                "@ag-grid-community/vue3": "https://unpkg.com/@ag-grid-community/vue3@25.3.0/",
                "ag-grid-community": "https://unpkg.com/ag-grid-community@25.3.0/",
                "ag-grid-enterprise": "https://unpkg.com/ag-grid-enterprise@25.3.0/",
                "ag-grid-angular": "https://unpkg.com/ag-grid-angular@25.3.0/",
                "ag-grid-react": "https://unpkg.com/ag-grid-react@25.3.0/",
                "ag-grid-vue3": "https://unpkg.com/ag-grid-vue3@25.3.0/"
            };
            var systemJsPaths = {
                "@ag-grid-community/all-modules": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/ag-grid-community.cjs.js",
                "@ag-grid-community/client-side-row-model": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/ag-grid-community.cjs.js",
                "@ag-grid-community/core": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/ag-grid-community.cjs.js",
                "@ag-grid-community/csv-export": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/ag-grid-community.cjs.js",
                "@ag-grid-community/infinite-row-model": "https://unpkg.com/@ag-grid-community/all-modules@25.3.0/dist/ag-grid-community.cjs.js"
            };
        </script>
		<script src="https://unpkg.com/systemjs@0.19.47/dist/system.js">
		</script>
		<script src="systemjs.config.js">
		</script>
		<script>System.import('./index.jsx').catch(function(err) { console.error(err); });</script>
	</body>
</html>