demo ยท v139

Blocking Attribute Matrix

Compare the standard blocking="render" token with Chrome 139's experimental blocking="full-frame-rate" token, then probe the real element.blocking DOMTokenList and simulate the frame-rate restore rules.

Origin-trial context: ChromeStatus describes full-frame-rate as an experimental token for <link rel="expect" href="#critical-content">. The browser may lower frame rate before the element is parsed and may restore it early after a timeout or user interaction, so this page pairs real DOM reflection with a faithful timeline simulation.

Token matrix

Token Primary effect Typical element Status
render Blocks rendering until the blocking condition is cleared. <link>, <script>, <style> HTML token
full-frame-rate Lowers frame rate during loading so parsing and resource work can use more budget. <link rel="expect" href="#critical-content"> Chrome 139 experiment
full-framerate Legacy proposal spelling from the WHATWG issue text. Do not ship this spelling. None Wrong spelling

Live element builder


  


  

    
Real DOMTokenList probe

    
The checks below create the selected element in JavaScript, set its blocking attribute, read back element.blocking, and test supported-token behavior.

    

  


  

    
Frame-rate impact model

    

      

        First paint
        160ms
        
Paint is not fully blocked by full-frame-rate alone.

      

      

        First full-rate frame
        900ms
        
Full-rate rendering resumes after the expected content parses.

      

      

        Low-frame-rate window
        740ms
        
Informative throttling window, not a hard web-exposed promise.

      

    

    

  


  

    
Failure and boundary branches

    

  


  

    
see also