NotRestoredReasons

Limited availability

The NotRestoredReasons interface of the Performance API provides report data containing reasons why the current document was blocked from using the back/forward cache (bfcache) on navigation.

These objects are accessed via the notRestoredReasons property.

Instance properties

• children Read only Experimental
  • : An array of NotRestoredReasons objects, one for each child <iframe> embedded in the current document, which may contain reasons why the top-level frame was blocked relating to the child frames. Each object has the same structure as the parent object — this way, any number of levels of embedded <iframe>s can be represented inside the object recursively. If the frame has no children, the array will be empty; if the document is in a cross-origin <iframe>, children will return null.
• id Read only Experimental
  • : A string representing the id attribute value of the <iframe> the document is contained in (for example <iframe id="foo" src="/firefox/mdn-asset-missing.svg">). If the document is not in an <iframe> or the <iframe> has no id set, id will return null.
• name Read only Experimental
  • : A string representing the name attribute value of the <iframe> the document is contained in (for example <iframe name="bar" src="/firefox/mdn-asset-missing.svg">). If the document is not in an <iframe> or the <iframe> has no name set, name will return null.
• reasons Read only Experimental
  • : An array of NotRestoredReasonDetails objects, each representing a reason why the navigated page was blocked from using the bfcache. If the document is in a cross-origin <iframe>, reasons will return null, but the parent document may show a reason of "masked" if any <iframe>s blocked bfcache usage for the top-level frame.
• src Read only Experimental
  • : A string representing the path to the source of the <iframe> the document is contained in (for example <iframe src="/firefox/mdn-asset-missing.svg">). If the document is not in an <iframe>, src will return null.
• url Read only Experimental
  • : A string representing the URL of the navigated page or <iframe>. If the document is in a cross-origin <iframe>, url will return null.

Instance methods

• toJSON() Experimental
  • : A serializer; returns a JSON representation of the NotRestoredReasons object.

Examples

See Monitoring bfcache blocking reasons for examples.

Specifications

Browser compatibility

See also

• Monitoring bfcache blocking reasons
• notRestoredReasons