6 replies

1. Mike Samuel 16 min later

   @zachleat Doesn't it need to bootstrap a whole new Realm with its own copy of the intrinsics?

   $ node
   Welcome to Node.js v19.6.0.
   Type ".help" for more information.
   > let otherArray = vm.runInContext('Array', vm.createContext())
   undefined
   > Array === otherArray
   false
   >
   

   1. Mike Samuel 33 min later

      @zachleat If you need a way to create a light-weight scope to prevent unintentional bleed of "global" assignments, you can do tricks via with over a Proxy over globals.

      globalThis.x = 'global.x';
      
      let localGlobal = Object.create(globalThis);
      
      let p = new Proxy(
          localGlobal,
          {
              has(obj, prop) {
                  return true;
              },
              get(obj, prop) {
                  if (prop === 'globalThis') { return localGlobal }
                  return obj[prop];
              },
          }
      );
      
      
      with (p) {
          console.log('x before assignment', x);     // => global.x
          x = 'local-this';
          console.log('x after assignment', x);      // => local-this
          console.log('globalThis.x', globalThis.x); // => local-this
      }
      console.log('x outside `with`', x);            // => global.x
      
      

      Doesn't provide mutual suspicion and doesn't solve functions that return the global scope but keeps a lid on unintentional interference.

      1. Zach Leatherman 42 min later

         @mvsamuel yeah! I did something similar, though with a scoped object that I could blow away for a cheap clean slate

   2. Zach Leatherman 40 min later

      @mvsamuel Yeah, I believe so!

2. Zach Leatherman 2 hr later

   Here it is!

   https://fosstodon.org/@eleventy/110029514364983609

   1. Joshua Kinal 2 hr later

      @zachleat get out of town! 👏🏼👏🏼👏🏼👏🏼👏🏼👏🏼