Word boundary won't match start or end in javascript

Question

I get unexpected results with this code:

'foo'.match(new RegExp('\bfoo\b')); // Returns null 

Why does this return null while this returns "foo"?

 'foo'.match(new RegExp('foo')); // Returns "foo" 

Does the word boundary marker match the start and end?

EDIT: I need the regex to be a string because I am inserting variables into it.

Answer 1

Backslash Escape

 'foo'.match(new RegExp('\\bfoo\\b')); 

Answer 2

 "foo".match(/\bfoo\b/); 

gotta do it for you

Answer 3

Do not insert it in quotation marks ... instead, do the following: -

 'foo'.match(new RegExp(/\bfoo\b/))