什么是Cors-策略，为什么它不允许我在javascript中post请求中使用内容类型？

Question

当我在控制台中运行post请求时，它是这样显示的。

Access to fetch at 'http://dummy.restapiexample.com/api/v1/create' from origin 'http://127.0.0.1:5501' has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.
tut42.js:57 POST http://dummy.restapiexample.com/api/v1/create net::ERR_FAILED
postData @ tut42.js:57
(anonymous) @ tut42.js:61
tut42.js:57   Uncaught (in promise) TypeError: Failed to fetch
    at postData (tut42.js:57)
    at tut42.js:61
postData @ tut42.js:57
(anonymous) @ tut42.js:61
Promise.then (async)
postData @ tut42.js:58
(anonymous) @ tut42.js:61

Answer 1

作为跨域请求，API调用本身似乎被阻塞，您可以尝试单独添加访问控制允许标头，也可以切换到无cors模式。

fetch(request, {mode: 'cors'});

为了更好地理解CORS，请查看https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS。

对于可以与访问控制允许标头对应的不同标题，请在下面的链接https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Headers中显示

Access-Control-Allow-Headers: *