javascript - 向 Node 服务器发出请求未到达端点

Question

我正在尝试将 axios.post 从我的 React 前端发送到我的 Node 服务器! React 客户端和 Node 服务器都在本地运行 - 在同一父目录中。客户端在端口 3000 和服务器 3400 上运行。

当我将代码更改为 app.get 并访问 url localhost:3400/refundCalc 时，它会工作并在 res.send 时显示 hello 消息。它不能作为 app.post 工作，但也不能使用 axios post 工作!

错误代码为:加载失败http://localhost:3400/refundCalc :对预检请求的响应未通过访问控制检查:请求的资源上不存在“Access-Control-Allow-Origin” header 。来源'http://localhost:3000 ' 因此不允许访问。

我发布了所有的 React 前端代码，但实际上它只是 getRefundCalc 函数，我认为 axios.post 就是问题所在？

我的服务器代码:

const express = require('express');
const app = express();
const bodyParser = require('body-parser')
const port = 3400;
const server = app.listen(port, () => console.log(`Example app listening on port ${port}!`))
app.use(bodyParser.urlencoded({ extended: false }))

app.get('/', (req, res) => res.send('Hello World!'))


// to send the get refundCalcRequest
app.post('/refundCalc', function (req, res) {
    console.log('response from client - get refund request ' + res)
    console.log('request from client - get refund request ' + req)

    res.end('HELLOOOO')

})

我的 react 前端:

import React, { Component } from 'react';
import PropTypes from 'prop-types';
import { withStyles } from '@material-ui/core/styles';
import Card from '@material-ui/core/Card';
import CardActionArea from '@material-ui/core/CardActionArea';
import CardActions from '@material-ui/core/CardActions';
import CardContent from '@material-ui/core/CardContent';
import CardMedia from '@material-ui/core/CardMedia';
import Button from '@material-ui/core/Button';
import Typography from '@material-ui/core/Typography';
import axios from 'axios'

  class MediaCard extends Component {
  constructor(props) {

    super(props)
    this.state = {

    }

  }


  getRefundCalc(props) {
    console.log('we are calling the getrefundcalc call on button click')
    console.log('the props of the card, are they different for each card?' + JSON.stringify(props))

    axios.post(`http://localhost:3400/refundCalc`, { props }) <-- HERES THE CALL.
      .then(res => {
        console.log(res);
        console.log(res.data);
      })
  }




 render() {
    const { classes } = this.props;
    const rtnBtnClicked = this.state.rtnBtnClicked;
    return (
      <Card className={classes.card} onClick={() => this.getRefundCalc(this.props)}>
        <CardActionArea >
          <CardMedia
            className={classes.media}
            image={this.props.data.imageLinks.image_src}
          />
          <CardContent >
            <Typography gutterBottom variant="h5" component="h5" style={{ fontSize: 9 }}>
              {this.props.data.items.title}
            </Typography>
            <Typography component="h5" style={{ fontSize: 10 }}>
              Price:£ {this.props.data.items.price}
            </Typography>
          </CardContent>
        </CardActionArea>
        <CardActions>
          <Button size="small" color="primary" >
            {rtnBtnClicked ? 'Remove From Refund' : 'Add to Refund'}
          </Button>
        </CardActions>
      </Card>
    );
  }
}

我的预期结果是发布请求到达我的端点并控制台结果:D

Answer 1

const express = require('express');
const app = express();
const bodyParser = require('body-parser')
const corst = require('cors'); // requiring cors
const port = 3400;

app.use(cors()) // adding cors middleware to allow request from other domains
app.use(bodyParser.urlencoded({ extended: false }))

...
const server = app.listen(port, () => console.log(`Example app listening on port ${port}!`))