JSFiddle - React, Tailwind, and code Playground
JavaScript
var str = 'aaabbcapppp';
console.log( charSplit(str) );
function charSplit(str) {
var arr = {}, l, j = -1;
for (var i=0; i<str.length; i++) {
var c = str.charAt(i);
l==c ? arr[j] += c : arr[++j] = c;
l=c;
}
return arr;
}