Javascript code inside HTML

Hi my freinds, after choosing a target i tried directly this code <h1>hello</h1> inside the “chat help” , the word apears bigger and the code works

my idea is to put now a code of JS inside HTML tag

when i put <h1 onclick="alert('popup')">Click me!</h1>

Click me appears alone put it doesn’t give the hand to click on it!

who have good idea!?

thank you all