let favourites = $state([])

onMount(() => {
     //this is a network promise in the actual code
     Promise.resolve({"favourites": [1, 2, 3]}).then(res => {


           //-----this causes the state to not update
           favourites = res["favourites"];
           //----


           //===but when using this, it works
           favourites.length = 0;
           for(let a of res["favourites"]){
                 favourites.push(a);
           }
           //====


     })
})