How do I get the index of a container in a repeater and change the color per container?

[Cue]

let arrayy = [a,b,c,d]
$w(“#repeaterfill”).onItemReady(($item,itemData,index=>{
$item (“#Title”). text= itemData . title ;
}
for(let i=0; i<arrayy.length;i++){
let fill = wixData.query(“ALL”)
.eq(“allid”,array[i])
Promise.all([fill.limit(1000).find()])
.then((res)=>{
let returned = [res[0].items].flat()
$w(“#repeaterfill”).container[i].backgroundcolor = “red”// trying to get something like this
$w(“#repeaterfill”).data[i] = returned[i]
})
}