XMLHttpRequest 无法加载 XXX 没有 \'Access-Control-Allow-Origin\' 标头答案

【问题标题】：XMLHttpRequest cannot load XXX No 'Access-Control-Allow-Origin' headerXMLHttpRequest 无法加载 XXX 没有 \'Access-Control-Allow-Origin\' 标头
【发布时间】：2022-12-02 18:40:09
【问题描述】：

tl;dr; About the Same Origin Policy

I have a Grunt process which initiates an instance of express.js server. This was working absolutely fine up until just now when it started serving a blank page with the following appearing in the error log in the developer\'s console in Chrome (latest version):

XMLHttpRequest cannot load https://www.example.com/ No \'Access-Control-Allow-Origin\' header is present on the requested resource. Origin \'http://localhost:4300\' is therefore not allowed access.

What is stopping me from accessing the page?

I\'m working on the website and it was fine five minutes ago.
does it issue CORS headers? perhaps if you shared some code it would be easier to see
Plausibly. Which department should I ask to find out? I just do the backbone.marionette stuff mostly...
Yeah. I suppose the organisations of departments isn\'t always uniform anyway, so it is possibly a nebulous question but I would like to know a bit of the backend/routing/sys-admin stuff at my company and this seemed like a good excuse to familiarise myself so if there are problems in future I can help out.
I would ask someone on the server side inside your operation. They must have changed it on you if you were able to access it before.

标签： javascript cors same-origin-policy

【解决方案1】：

【解决方案2】：

【解决方案3】：

【解决方案4】：

【解决方案5】：

【解决方案6】：

【解决方案7】：

【解决方案8】：

【解决方案9】：

【解决方案10】：

【解决方案11】：