The main thing to consider here is that you have a series (list) of nouns, in this case consisting of three items:
its attributes, [its] text or a pattern in the text
The possessive pronoun its is understood to be distributed through the list, which is why you are correct, and it is acceptable to omit it. Further examples of this with articles:
Laura bought an apple, peach, pear, and plum.
He is the judge, jury and executioner.
And with possessive pronouns:
He likes his dog because of its color, temperament, and intelligence.
I hired John because of his work ethic, programming skills, and excellent references.
Note, that it is also acceptable to keep the article/pronoun, and this is often done for emphasis/style:
the truth, the whole truth, and nothing but the truth