console.log(uncamelize('helloWorld'));
console.log(uncamelize('helloWorld','-'));
console.log(uncamelize('helloWorld','_'));

function uncamelize(str,ch)
{
    var temp = str.split('')
    var arr = [];
    for(var i=0 ;i<str.length ; i++)
    {
        if(temp[i] == temp[i].toUpperCase())
        {
            arr[i] = ch;
            arr.push(temp[i])
            continue
        }
        arr.push(temp[i]);
    }
    return arr.join('')
}