count consecutive char freq

charfreq.js

    var k = "aaahhrrrvfuuhh".split("")
    var ref = k[0]
    var newStr = ''

    while(k.length) {
        for(var i=0;i<k.length;i++) {
            if(k[i] != ref) {
            console.log(k[i] , ref, i)
                k = k.splice(i,k.length - 1)
                if(i > 1) {
                    newStr += ref + i
                } else {
                    newStr += ref
                }
                break;
            } else {
                console.log("ELSE")
            }
        }
        ref = k[0]
        console.log(k, k.length, k[i], ref)
        if(!k[i]) {
            newStr += ref + k.length
            k = [];
            break;
        }
    }
    console.log(newStr)

output

"a3h2r3vfu2h2"