为什么不添加CORS头选项路由允许浏览器访问我的API?

我试图在使用Express.js web框架的Node.js应用程序中支持CORS。我已经阅读了谷歌关于如何处理这个问题的小组讨论，并阅读了一些关于CORS如何工作的文章。首先，我这样做(代码是用CoffeeScript语法写的):

app.options "*", (req, res) ->
  res.header 'Access-Control-Allow-Origin', '*'
  res.header 'Access-Control-Allow-Credentials', true
  # try: 'POST, GET, PUT, DELETE, OPTIONS'
  res.header 'Access-Control-Allow-Methods', 'GET, OPTIONS'
  # try: 'X-Requested-With, X-HTTP-Method-Override, Content-Type, Accept'
  res.header 'Access-Control-Allow-Headers', 'Content-Type'
  # ...

这似乎不管用。似乎我的浏览器(Chrome)没有发送最初的选项请求。当我刚刚更新了块的资源，我需要提交一个跨起源GET请求:

app.get "/somethingelse", (req, res) ->
  # ...
  res.header 'Access-Control-Allow-Origin', '*'
  res.header 'Access-Control-Allow-Credentials', true
  res.header 'Access-Control-Allow-Methods', 'POST, GET, PUT, DELETE, OPTIONS'
  res.header 'Access-Control-Allow-Headers', 'Content-Type'
  # ...

它工作(在Chrome)。这也适用于Safari。

我听说……

在实现CORS的浏览器中，每个跨源GET或POST请求之前都有一个OPTIONS请求，用于检查GET或POST是否正常。

所以我的主要问题是，为什么这种情况在我身上没有发生?为什么我的app。options块没有被调用?为什么我需要在我的主app.get块设置标题?

当前回答

使用Express Middleware非常适合我。如果您已经在使用Express，只需添加以下中间件规则。它应该开始工作了。

app.all("/api/*", function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "Cache-Control, Pragma, Origin, Authorization, Content-Type, X-Requested-With");
  res.header("Access-Control-Allow-Methods", "GET, PUT, POST");
  return next();
});

app.all("/api/*", function(req, res, next) {
  if (req.method.toLowerCase() !== "options") {
    return next();
  }
  return res.send(204);
});

参考

2018-08-29 18:29:52

其他回答

我们可以避免CORS，而是将请求转发到另一个服务器:

// config:
var public_folder = __dirname + '/public'
var apiServerHost = 'http://other.server'

// code:
console.log("starting server...");

var express = require('express');
var app = express();
var request = require('request');

// serve static files
app.use(express.static(public_folder));

// if not found, serve from another server
app.use(function(req, res) {
    var url = apiServerHost + req.url;
    req.pipe(request(url)).pipe(res);
});

app.listen(80, function(){
    console.log("server ready");
});

2016-05-15 08:45:22

可以参考下面的代码相同。来源:Academind / node-restful-api

const express = require('express');
const app = express();

//acts as a middleware
//to handle CORS Errors
app.use((req, res, next) => { //doesn't send response just adjusts it
    res.header("Access-Control-Allow-Origin", "*") //* to give access to any origin
    res.header(
        "Access-Control-Allow-Headers",
        "Origin, X-Requested-With, Content-Type, Accept, Authorization" //to give access to all the headers provided
    );
    if(req.method === 'OPTIONS'){
        res.header('Access-Control-Allow-Methods', 'PUT, POST, PATCH, DELETE, GET'); //to give access to all the methods provided
        return res.status(200).json({});
    }
    next(); //so that other routes can take over
})

2018-09-25 12:29:08

简单很难:

 let my_data = []
const promise = new Promise(async function (resolve, reject) {
    axios.post('https://cors-anywhere.herokuapp.com/https://maps.googleapis.com/maps/api/directions/json?origin=33.69057660000001,72.9782724&destination=33.691478,%2072.978594&key=AIzaSyApzbs5QDJOnEObdSBN_Cmln5ZWxx323vA'
        , { 'Origin': 'https://localhost:3000' })
        .then(function (response) {
            console.log(`axios response ${response.data}`)
            const my_data = response.data
            resolve(my_data)
        })
        .catch(function (error) {
            console.log(error)
            alert('connection error')
        })
})
promise.then(data => {
    console.log(JSON.stringify(data))
})

2020-03-03 10:13:05

使用Express Middleware非常适合我。如果您已经在使用Express，只需添加以下中间件规则。它应该开始工作了。

app.all("/api/*", function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "Cache-Control, Pragma, Origin, Authorization, Content-Type, X-Requested-With");
  res.header("Access-Control-Allow-Methods", "GET, PUT, POST");
  return next();
});

app.all("/api/*", function(req, res, next) {
  if (req.method.toLowerCase() !== "options") {
    return next();
  }
  return res.send(204);
});

参考

2018-08-29 18:29:52

安装expressjs的cors模块。你可以按照这些步骤来做

安装

npm install cors

简单使用(启用所有CORS请求)

var express = require('express');
var cors = require('cors');
var app = express();
app.use(cors());

欲了解更多详情，请访问https://github.com/expressjs/cors

2016-06-15 20:37:36

为什么不添加CORS头选项路由允许浏览器访问我的API?

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