CPRS解决跨域问题 -- 基于vue-cli创建的demo项目日记 - NodeJS+Express建站日记

问题

在前端（http://localhost:8080）异步向后端服务（http://localhost:3000）发出请求，报错：

XMLHttpRequest cannot load http://192.168.102.82:3000. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8080' is therefore not allowed access.

查找资料，跨域主要问题在header.

header详解：http://kb.cnblogs.com/page/92320/

于是，了解header，对header进行设置，问题迎刃而解了。

解决

1、Access-Control-Allow-Origin 允许的域

2、Access-Control-Allow-Headers 允许的header类型

3、Access-Control-Allow-Methods 允许的header请求类型

代码如下：

//解决跨域问题
app.all('*',function (req, res, next) {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Headers', 'Content-Type, Content-Length, Authorization, Accept, X-Requested-With , yourHeaderFeild');
  res.header('Access-Control-Allow-Methods', 'PUT, POST, GET, DELETE, OPTIONS');

  if (req.method == 'OPTIONS') {
    res.send(200);
  }
  else {
    next();
  }
});

参考资料：http://cnodejs.org/topic/51dccb43d44cbfa3042752c8