[laimas]

alert('AAAADEEESSQQQQQQ'.split('').reduce(function(m, c, i, a) {
    if(c == a[i+1]) m[m.length-1]++; 
    else {
        m[m.length-1] = c+m[m.length-1];  
        if(a[i+1]) m.push(1);
    }
    return m
}, [1]).join(''));