preflight response 應該是異步的什么問題---后來發現不是，是axios參數格式問題，網上其他一些解答太誤導人了

Request header field Content-Type is not allowed by Access-Control-Allow-Headers in preflight response.

用的axios做的請求，express后端返回，post請求時報這個錯

設置Axios.post('/api-user/login/login', params, {headers: {'sign': sign}}); 后面的sign時報

　　Request header field sign is not allowed by Access-Control-Allow-Headers in preflight response.

 

 

原因？求解

----------------------------------------------------------

let params={name:'hhl',psd:'123456'};
let out=Axios.get('/login',{params:params});  //格式不這么寫就報 in preflight response

let out2=Axios.post('/login/abort', qs.stringify(params) ); //post需要用qs來轉化一下

axios沒有配置什么，express配置跨域

app.all('*', function(req, res, next) {
　　res.header("Access-Control-Allow-Origin", "*");
　　res.header("Access-Control-Allow-Headers", "X-Requested-With");
　　res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
　　res.header("X-Powered-By",' 3.2.1');
　　res.header("Content-Type", "application/json;charset=utf-8");
　　next();

}

其中主要是origin，好像

問題已解決