What's the fastest way to check if a word from one string is in another string?

Question

I have a string of words; let\'s call them bad:

bad = \"foo bar baz\"

I can keep this string as a whitespace separated string,

Answer 1

bad = "foo bar baz"

=> "foo bar baz"

str = "This is my first foo string"

=> "This is my first foo string"

(str.split(' ') - bad.split(' ')).join(' ')

=> "This is my first string"