Adding extra zeros in front of a number using jQuery?

Question

I have file that are uploaded which are formatted like so

MR 1

MR 2

MR 100

MR 200

MR 300

Answer 1

str could be a number or a string.

formatting("hi",3);
function formatting(str,len)
{
   return ("000000"+str).slice(-len);
}

Add more zeros if needs large digits