setHeader cors

원래 코드

app.use((req, res, next) => {
  res.setHeader("Access-Control-Allow-Origin", [
    "http://localhost:3000",
    // "http://asmallgoodthing.s3-website.ap-northeast-2.amazonaws.com",
  ]);
...
});

1차 수정 - 실패

app.use((req, res, next) => {
  console.log("Serving request type " + req.method + " for url " + req.url);
  [
    "http://localhost:3000",
    "http://asmallgoodthing.s3-website.ap-northeast-2.amazonaws.com",
  ].map(function(domain) {
    res.setHeader( "Access-Control-Allow-Origin", domain );
  });
...
});

2차 수정

app.use((req, res, next) => {
  console.log("Serving request type " + req.method + " for url " + req.url);
  const allowedOrigins = [
    "http://localhost:3000",
    "http://asmallgoodthing.s3-website.ap-northeast-2.amazonaws.com",
  ];
  const origin = req.headers.origin;
  if(allowedOrigins.indexOf(origin) > -1){
    res.setHeader('Access-Control-Allow-Origin', origin);
  }
...
});

참고