Inserting string at multiple position of another string using JavaScript

Question

I have 2 vars and need to insert b into a after evry "}" and befor any css classes. How can I do this with jquery or javascript?

var a        = "p{font-size:20px}
                .tihais {font-weight:bold}";
var b        = "#afnay";
var position = after evry "}";

thx

Answer 1

var a        = "p{font-size:20px}
            .tihais {font-weight:bold}";
var b        = "}#afnay"; // This variable value is changed!
a= a.replace("}", b);

Answer 2

var a = 'p{font-size:20px}\n'+
'.tihais {font-weight:bold}';
var b = "}#afnay";    
a= a.replace(/}/g, b);
console.log(a)