javascript - jquery uses the post method to request data, how to pass parameters in the header?

I found this method on the Internet:
$.ajax({

<code> //请求类型，这里为POST
 type: 'POST',
 //你要请求的api的URL
 url: url ,
 //是否使用缓存
 cache:false,
 //数据类型，这里我用的是json
 dataType: "json", 
 //必要的时候需要用JSON.stringify() 将JSON对象转换成字符串
 data: JSON.strigify({key:value}), //data: {key:value}, 
 //添加额外的请求头
 headers : {'Access-Control-Allow-Origin':'*'},
 //请求成功的回调函数
 success: function(data){
    //函数参数 "data" 为请求成功服务端返回的数据</code>

},
});
But prompt:
Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers in preflight response.
Already in the php code Access-Control-Allow- The value of Headers is set to *, but an error is still reported. Is there any solution?

Reply content:

I found this method on the Internet:
$.ajax({

<code> //请求类型，这里为POST
 type: 'POST',
 //你要请求的api的URL
 url: url ,
 //是否使用缓存
 cache:false,
 //数据类型，这里我用的是json
 dataType: "json", 
 //必要的时候需要用JSON.stringify() 将JSON对象转换成字符串
 data: JSON.strigify({key:value}), //data: {key:value}, 
 //添加额外的请求头
 headers : {'Access-Control-Allow-Origin':'*'},
 //请求成功的回调函数
 success: function(data){
    //函数参数 "data" 为请求成功服务端返回的数据</code>

},
});
But prompt:
Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers in preflight response.
Already in the php code Access-Control-Allow- The value of Headers is set to *, but an error is still reported. Is there any solution?

First of all, let’s talk about why the preflight problem occurs. That’s because your request is no longer a “simple request”. In cross-domain issues, some requests that combine specific conditions are often called simple requests, and those that satisfy “simple requests” The conditions for "Request" are as follows:

The request type must be one of GET, POST, HEAD
The request header (Header) can only contain:

• Accept

• Accept Language

• Content Language

• Last Event ID

• Content Type: only accept application/x-www-form-urlencoded, multipart/form-data, text/plain

Your problem is that, obviously, you added a header Access-Control-Allow-Origin, causing the request to become "not simple". When the request is not simple, the browser will first send a so-called preflight request for security reasons with the method OPTIONS

For more information about cross-domain, it is recommended to read Building public APIs and CORS

I understand your problem. It should be fine if you remove the extra header