Hey, firstly, great article!
However, in your regex replace example, I believe something's missing?
Running the following will throw an error: Uncaught ReferenceError: str is not defined
var heyStr = "Hey now!";
var byeStr = "Bye";
var res = str.replace("Hey", "Bye")//returns ;
Shouldn't res = heyStr.replace("Hey", "Bye") ?
Similarly, the str.search() example is missing. Let me know if I'm missing something?