javascript - CORS 与 Express.js 和 Angular2

Question

我正在尝试从我的远程 Express.js 服务器下载一个 PLY 文件到我的 Angular/Ionic 应用程序。我现在在 Amazon AWS 上托管了我的 Ionic 应用程序。这是来自 Ionic 应用程序的 Typescript:

//this.currentPlyFile encompasses entire URL
document.getElementById('entity').setAttribute("ply-model", "src: url(" + this.currentPlyFile + ".ply);");

我的 Express.js 服务器中有以下内容:

app.use(function(req, res, next) {
        res.header('Access-Control-Allow-Credentials', true);
        res.header('Access-Control-Allow-Origin', '*');
        res.header('Access-Control-Allow-Methods', 'GET,POST');
        res.header('Access-Control-Allow-Headers', 'appid, X-Requested-With, X-HTTP-Method-Override, Content-Type, Accept');
        if ('OPTIONS' == req.method) {
            res.send(200);
        } else {
            next();
        }
    });

但是在请求 PLY 文件时出现以下错误:

XMLHttpRequest cannot load "my url here" No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'my url here' is therefore not allowed access.

这真的很令人沮丧，因为我正在使用 Express.js 文档提供的 header 来允许 CORS。

Answer 1

预检 -> 选项 -> https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS -> 下一步()

app.use(function(req, res, next) {
    res.header('Access-Control-Allow-Credentials', true);
    res.header('Access-Control-Allow-Origin', '*');
    res.header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
    res.header('Access-Control-Allow-Headers', 'appid, X-Requested-With, X-HTTP-Method-Override, Content-Type, Accept');
    next();
});

app.get('/', function (req, res) {
  res.send('OK');
});

注意:将这些内容移到配置函数的顶部。

---

或者简单使用express cors :

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

app.use(cors());

app.get('/', function (req, res) {
    res.send('OK');
});