IE開發工具文檔模式用戶代理

Question

將文檔模式設置爲默認值以外的值不會在請求中發送相應的User-Agent標頭（如在IE devtools的網絡選項卡中所見）。但是，在控制檯中執行navigator.userAgent確實反映了適當的字符串（與文檔模式/用戶代理設置關聯）。

這是IE開發工具中的一個bug嗎？如果不是，那麼讓IE將相應的User-Agent標頭髮送到遠程服務器的正確方法是什麼？

Answer 1

在JavaScript中，document.documentMode映射到F12開發人員工具。用戶代理不受影響：

務必：

使用以下幾種檢測方法更可靠地檢測誤差的來源，並確保您的網頁在不同瀏覽器兼容：

Feature detection: Test whether a browser supports a feature before you use it. Feature detection enables cross-browser code to "just work" without requiring you to know the capabilities of every browser ahead of time. For example, the jQuery framework relies almost entirely on feature detection. For more info about how you can use jQuery's feature detection in your own site, see the jQuery.support documentation. 
Behavior detection: Test for known issues before you apply a workaround. jQuery also uses behavior detection by running tests for known issues to determine if certain workarounds are needed. 

不要：

Detect specific browsers: Don't use the identity of a browser (for example, navigator.userAgent) to change a page's behavior. If you change code based on a specific browser, the page cannot easily adapt to changes and it might break when a new browser is released. In other situations, pages use a legacy workaround even when that workaround is no longer needed. 
Assume unrelated features: Don't perform feature detection for one feature and then use a different feature. Sites that have this problem perform feature detection for one feature and then use other features without testing whether they are supported. 

個

參考

• Internet Explorer compatibility cookbook | Compatibility guidelines and best practices: Use feature and behavior detection