C# Web API OPTION 跨域問題

C# Web API 由於默認對 OPTION 請求的不一樣的處理，導致部分會通過 OPTION 請求來檢測是否可跨域的瀏覽器，在跨域時總是還沒開始就被拒絕。

處理辦法

在 Web.config 中配置跨域，修改默認配置。

重點先行，註釋掉以下這句

      <!--<remove name="OPTIONSVerbHandler" />-->

相關配置結果

  <system.webServer>
    <handlers>
      <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
      <!--<remove name="OPTIONSVerbHandler" />-->
      <remove name="TRACEVerbHandler" />
      <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
    </handlers>
    <httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*" />
        <add name="Access-Control-Allow-Headers" value="Origin, X-Requested-With, Content-Type, Accept, WG-App-Version, WG-Device-Id, WG-Network-Type, WG-Vendor, WG-OS-Type, WG-OS-Version, WG-Device-Model, WG-CPU, WG-Sid, WG-App-Id, WG-Token, token" />
        <add name="Access-Control-Allow-Methods" value="POST, GET, OPTIONS, PUT, DELETE" />
        <add name="Access-Control-Allow-Credentials" value="false" />
      </customHeaders>
    </httpProtocol>
  </system.webServer>