Zipp

Sandbox playground

Edit JavaScript and run it in a ZIPP sandbox. Nothing outside the program is permitted until you switch it on: storage, files, the network and host functions each have a switch, and steps and time each have a limit. The output shows what the program printed, and the refusal or limit that stopped it.

Loading the ZIPP sandbox…

Program

Output

Not run yet 

      
    


    

      
Permissions and limits

      

        Permissions
        

          
          
A private, in-memory localStorage, seeded with this data. Without it, localStorage throws a SecurityError.

          
          
        

        

          
          
Paths and their text, read with host.callSync("fs.read", path), "fs.list" and "fs.exists".

          
          
          
        

        

          
          
A fetch that reaches only these origins or URL prefixes, one per line, with no cookies. Without it, fetch does not exist. This page's own security policy lets the browser reach only this site, so another allowed origin still fails here.

          
          
        

        

          
          
The page answers host.call("page.time", …) and host.call("dice.roll", …). Without them, every host.call answers denied.

        

      

      

        Limits
        
        
        
Instructions the engine may run in total, at most 2,000,000,000. Past it the engine stops the program with a resource error.

        
        
        
How long the run may take. Each sandbox runs in its own Worker, and the page terminates the Worker when the time is up (timeout). With the default 50,000,000 steps an endless loop usually runs out of steps first.

      

    


    

      
The same sandbox in your page

      
With the files of a release beside your page: the loader zipp.mjs from zipp-<version>-wasm-embed-kit.zip, and the engine module.