Express应用程序上的访问源问题

Question

我用angular ui创建了一个快速应用程序。我已经关注了app.js文件

var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');

var indexRouter = require('./routes/index');
var userRouter = require('./routes/user');

var app = express();

// view engine setup
app.use(express.static(__dirname + '/dist'));

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next();
});


app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/student', userRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next(createError(404));
});



// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

我遇到这样的错误

request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin. is therefore not allowed access.

Answer 1

尝试一次设置多个字段，将一个对象作为参数传递。例如， import { format } from 'date-fns';

Answer 2

您可以像这样实现并检查吗？

OR

如果您现在想快速工作，可以使用chrome的hack代码。运行这个

在Windows中，将此命令粘贴到运行窗口中 chrome.exe --user-data-dir =“ C：/ Chrome开发者会话” --disable-web-security

Answer 3

实际上，必须从服务器端（API）解决此问题。如果您正在本地进行测试或在其他域中，则必须允许API实施中的CORS。

Answer 4

您可以将chrome的CORS扩展名用于开发目的