replace multiple character in a string?

replace multiple character in a string?

Hi, Jquery has given me the chance to learn new things on web development...I just have a question on the replace() function..... how can i change or replace multiple characters in a string. Is it possible? =)

example:

mystr  =    "i am new to jquery, it good to be updated";

char1="e";
char2="o";

in the given, i want that all "e" and "o" should have a background color, or perhaps make its font-weight to bold. Assuming that the mystr is inside <p> tag. please help.....