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Derived isn't mutated when reassigned synchronously after definition #15590

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thes01 opened this issue Mar 22, 2025 · 0 comments · May be fixed by #15592
Open

Derived isn't mutated when reassigned synchronously after definition #15590

thes01 opened this issue Mar 22, 2025 · 0 comments · May be fixed by #15592

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@thes01
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thes01 commented Mar 22, 2025 •
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Describe the bug

I just wanted to give the new mutable deriveds a try and did a simple test:

let thing = $derived(state); // or just $derived('old')
thing = 'new';

However, in the output, I still see the old value, not the updated one.

Note: this works

let thing = $derived('old');
Promise.resolve().then(() => { thing = 'new' });

UPDATE: If you put a console.log before the reassignment, then it starts working.

Reproduction

https://svelte.dev/playground/f447b4a9ec5d4271a9d1b187ab91a560?version=5.25.2

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annoyance

      		
    

      
  





        



            

              
            

        

      


      
    








      

    



      

  
          

  

    
  


  

      

    @paoloricciuti
paoloricciuti



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      Mar 22, 2025
    

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      fix: set deriveds as CLEAN if they are assigned to

    
      sveltejs/svelte
    





      
    

  




      

    

  
      

  

    

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          @thes01