unter > 5000) return;
      counter++;
      allocateMemory();
    })();
    
    console.log("Main job ends");
    // Logs:
    // Main job ends
    // Array gets garbage collected at 5001
    

However, if you allow a little break between each allocation, the callback may
be called sooner:

js

    
    
    let arrayCollected = false;
    let counter = 0;
    const registry = new FinalizationRegistry(() => {
      console.log(`Array gets garbage collected at ${counter}`);
      arrayCollected = true;
    });
    
    registry.register(["foo"]);
    
    (function allocateMemory() {
      // Allocate 50000 functions â a lot of memory!
      Array.from({ length: 50000 }, () => () => {});
      if (counter > 5000 || arrayCollected) return;
      counter++;
      // Use setTimeout to make each allocateMemory a different job
      setTimeout(allocateMemory);
    })();
    
    console.log("Main job ends");
    

There's no guarantee that the callback will be called sooner or if it will be
called at all, but there's a possibility that the logged message has a counter
value smaller than 5000.

##  Specifications

Specification  
---  
[ ECMAScript Language Specification  
#  sec-finalization-registry-objects
](https://tc39.es/ecma262/multipage/managing-memory.html#sec-finalization-
registry-objects)  
  
##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ ` WeakRef ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakRef)
  * [ ` WeakSet ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet)
  * [ ` WeakMap ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap)

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