Count repeated letters in a string

Question

I\'m stuck with the following problem: I need to find repeated characters in a string. Basically what I want is regular expression that will match like that

Answer 1

function charCount(str){
    let arr = str.split('');
    return arr.reduce((a,p)=>{
        a[p] = a[p] ? (a[p]+1) : 1;
        return a;
    },{});
};