Please how do get ride of this uncaught syntax error....invalid regular expression flags. it is being unable to run

Tell us what’s happening:

Your code so far

< p1 >this is a paragraph</p1>

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36.

Challenge: Say Hello to HTML Elements

Link to the challenge:

Hi @akwarichidex4 !

You will need to update your browser in order to get rid of the error message.

Also, you will need to reset the challenge.
p1 is not a valid html tag.

Your task is to change the h1 text.

FCC instructions:
To pass the test on this challenge, change your h1 element’s text to say Hello World .

Ok.thanks dear
Lete try that