JavaScript Count Duplicate Characters in a String Best way

test.js

function duplicateCharCount(str) {
		
	if(str) {
		var obj = {};
		for(let i = 0; i < str.length; i++) {
			if(obj[str[i]]){
				obj[str[i]] += obj[str[i]];
			}else {
				obj[str[i]] = 1;
			}
		}
		console.log(obj);
	}
			
}


Run this Code > 
  
duplicateCharCount("aabcdd");

Output >
  
  {a: 2, b: 1, c: 1, d: 2}

let str= 'CormSquare';
let obj= {}
for(val of str){
obj[val] = (obj[val] || 0) + 1
}
console.log(obj)

Output: { C: 1, o: 1, r: 2, m: 1, S: 1, q: 1, u: 1, a: 1, e: 1 }