How to use the vega.version function in vega

import React from 'react';
import ReactDOM from 'react-dom';
import * as ReactGA from 'react-ga';
import {Provider} from 'react-redux';
import {hashHistory, Route, Router} from 'react-router';
import * as vega from 'vega';
import * as vl from 'vega-lite';

import App from './components/app';
import configureStore from './store/configure-store';

window.VEGA_DEBUG = window.VEGA_DEBUG || {};
window.VEGA_DEBUG.vega = vega;
window.VEGA_DEBUG.vl = vl;
window.VEGA_DEBUG.VEGA_VERSION = vega.version;
window.VEGA_DEBUG.VEGA_LITE_VERSION = vl.version;

// Configure history for react-router
const store = configureStore(hashHistory);

// Google analytics
ReactGA.initialize('UA-44428446-7');

function logPageView() {
  ReactGA.set({page: window.location.pathname + window.location.search});
  ReactGA.pageview(window.location.pathname + window.location.search);
}

// Now that redux and react-router have been configured, we can render the
// React application to the DOM!
ReactDOM.render(

import * as d3 from 'd3';
import * as vega from 'vega';
import * as vl from '../src/index';
import {TopLevelSpec} from '../src/spec';

d3.select('#vl-version').text(vl.version);
d3.select('#vg-version').text(vega.version);

function loadJSON(url: string, callback: (data: object) => void) {
  vega.loader().load(url).then(function(data: string) {
    callback(JSON.parse(data));
  });
}

loadJSON('examples/all-examples.json', function(examples: string[]) {
  const viz = d3.select('div.viz-list').selectAll('.viz').data(examples);

  viz.exit().remove();

  const vizEnter = viz
    .enter()
    .append('div')
    .attr('class', 'viz')

import styled from 'styled-components';
import {FORMAT, readVegaFile} from './utils/helper';
import {showOpenDialog} from './utils/dialog';

import DropArea from './components/DropArea';
import VegaRenderer from './components/VegaRenderer';
import downloadURI from './utils/downloadURI';

const vg = require('vega');
const vl = require('vega-lite');

window.VEGA_DEBUG = window.VEGA_DEBUG || {};
window.VEGA_DEBUG = {};
window.VEGA_DEBUG.vega = vg;
window.VEGA_DEBUG.vl = vl;
window.VEGA_DEBUG.VEGA_VERSION = vg.version;
window.VEGA_DEBUG.VEGA_LITE_VERSION = vl.version;

console.log('%cWelcome to Vega-Desktop!', 'font-size: 16px; font-weight: bold;');
console.log('You can access the Vega view with VEGA_DEBUG. Learn more at https://vega.github.io/vega/docs/api/debugging/.');

const MenuBar = styled.div`
  background-color: #eee;
  padding: 5px;
  position: fixed;
  width: 100%;
  z-index: 100;
`;

const StatusBar = styled.div`
  background-color: #efefef;
  padding: 5px 8px;

export function parseInputSpec(inputSpec, onWarning) {
  let spec = { ...inputSpec };

  if (!spec.$schema) {
    onWarning(`The input spec does not specify a "$schema", defaulting to "${DEFAULT_SCHEMA}"`);
    spec.$schema = DEFAULT_SCHEMA;
  }

  const schema = schemaParser(spec.$schema);
  const isVegaLite = schema.library === 'vega-lite';
  const libVersion = isVegaLite ? vegaLite.version : vega.version;

  if (versionCompare(schema.version, libVersion) > 0) {
    onWarning(
      `The input spec uses "${schema.library}" ${schema.version}, but ` +
      `current version of "${schema.library}" is ${libVersion}.`
    );
  }

  const hostConfig = spec._hostConfig;
  if (hostConfig !== undefined) {
    delete spec.hostConfig;
    if (typeof hostConfig !== 'object') {
      throw new Error('_hostConfig must be an object');
    }
  }

<div>
             {
                this.vega = c;
              }}
              className="vis"
              format={format}
              spec={spec}
              filePath={filePath}
            /&gt;
          </div>
        
        
          {format === FORMAT.VEGA_LITE ?
            `Vega-Lite v${vl.version}` :
            `Vega v${vg.version}`}
        
      
    );
  }
}