如何使用fetch（）javascript和Node ExpressJS忽略自签名证书警告？

我有一个运行NodeJS和ExpressJS的客户端服务器，它对后端API服务器进行API调用。但是，只要使用

fetch（）

调用API，后端API服务器就会抛出自签名证书错误警告

如何忽略自签名证书警告并使浏览器始终信任后端API服务器进行API调用

以下是错误：

下面是我如何使用fetch进行API调用：

  logInUser(userCredentials) {

    var userCredsBody = {
        'firstname': `${userCredentials.username}`,
        'password': `${userCredentials.password}`
    }

    var configuration = {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(userCredsBody)
    }

    return function(dispatch) {
      fetch('https://serverapi.com:8080/userInfo', configuration)
      .then(response => response.json())
      .then(response => {
        console.log('Successful and ', response)
      })
      .catch((error) => {
        console.log("Error: ", error)
      })
    }

下面是如何设置客户端NodeJS和ExpressJS的：

    var express = require('express');
    var cors = require('cors');
    var path = require('path');
    var config = require('../webpack.config.js');
    var webpack = require('webpack');
    var webpackDevMiddleware = require('webpack-dev-middleware');
    var webpackHotMiddleware = require('webpack-hot-middleware');
    var app = express();
    var compiler = webpack(config);

    app.use(cors());

    app.use(webpackDevMiddleware(compiler, {noInfo: true, publicPath: config.output.publicPath}));

    app.use(webpackHotMiddleware(compiler));

    app.use(express.static('./dist'));

    app.use('/', function (req, res) {
      res.header("Access-Control-Allow-Origin", "*");
      res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
      res.sendFile(path.resolve('client/index.html'))
    })

    var port = 3000;

    app.listen(port, function(error) {
      if (error) throw error;
      console.log("Express server listening on port", port);
    });