diff --git a/docs/api/web-contents.md b/docs/api/web-contents.md
index 2a9664f747..29bdc05a6a 100644
--- a/docs/api/web-contents.md
+++ b/docs/api/web-contents.md
@@ -147,6 +147,7 @@ Returns:
   `new-window`, `save-to-disk` and `other`.
 * `options` Object - The options which will be used for creating the new
   `BrowserWindow`.
+* `additional_features` Array - The non-standard features (features not handled by Chromium or Electron) given to `window.open()`. 
 
 Emitted when the page requests to open a new window for a `url`. It could be
 requested by `window.open` or an external link like `<a target='_blank'>`.
diff --git a/docs/api/window-open.md b/docs/api/window-open.md
index 0ecb9f6059..1e51d6b79a 100644
--- a/docs/api/window-open.md
+++ b/docs/api/window-open.md
@@ -25,8 +25,10 @@ Returns `BrowserWindowProxy` - Creates a new window and returns an instance of `
 The `features` string follows the format of standard browser, but each feature
 has to be a field of `BrowserWindow`'s options.
 
-**Note:** Node integration will always be disabled in the opened `window` if it
+**Notes:**
+* Node integration will always be disabled in the opened `window` if it
 is disabled on the parent window.
+* Non-standard features (that are not handled by Chromium or Electron such `this-is-not-a-standard-feature`) given in features will be passed to any registered `webContent`'s `new-window` event handler in the `additional_features` argument.
 
 ### `window.opener.postMessage(message, targetOrigin)`