const S = "aabcccccaaa"
const arr1 = [...S]
let array = []
let obj = {}
for(let i=0;i<arr1.length;i++){
if(array.length>0){
let item = array.find((item) =>
item.name == arr1[i]
)
if(item === undefined){
let newObj = {}
newObj.name = arr1[i]
newObj.num = 1
array.push(newObj)
} else {
item.num++
}
} else {
obj.name = arr1[i]
obj.num = 1
array.push(obj)
}
return array // [{name: 'a',num: 5},{name: 'b',num: 1},{name: 'c',num: 5}]
}